I have read through (or skimmed, honestly) almost all of the comments on this 8 page (to date) thread. At the risk of sounding/seeming/BEING dense, I honestly don't see the problem.
If you don't want to get married, don't get married. <shrug> What's the issue?
If you don't like the odds (as you perceive them) associated with marriage (as you perceive it) don't take the risk. <shrug>
There are, in my estimation, more socially acceptable ways of pairing available to any individual or couple, based on his/their preferences, than there has ever been in the history of paired off civilization. Please take advantage of this cornucopia of options. Don't get married. <shrug>
If all you want out of any social contract is sex on demand, it seems to me that there are a variety of options available to fulfill those needs, as long as you place yourself geographically such that you don't run afoul of secular laws in secular countries, religious laws in theocracies, and as long as you don't run afoul of basic human rights tenants in all countries involving the exploitation of the weak or the defenseless. Get your freak on in a sane, safe, consensual adult manner and don't get married. <shrug>
If you want to have a long-term monogamous relationship into which to introduce children but you don't want to risk your nest egg, then what you are saying is that you want to have a marriage without bringing your A game to the field. ??? Really? Is that the environment in which you wish to live? To raise future adults?
My peers call this "fear of commitment." My grandmother called it "Not ready to settle down." My mother called it "Doesn't know how to share." Notice she didn't say, "Can't share." Certainly we can all share. Knowing *how* to share is a process of learning the give and take of sharing successfully, and that requires the maturity to discern potentially successful give and take relationships from those doomed to failure. It doesn't take too many trips around the sand box before one learns that attempting to share with the playground bully usually doesn't work out too well. Not exactly the same but equally doomed to failure are sharing pairings based on dissimilar interests, unequal maturity levels, and unequal involvement. Hopefully we take those lessons into adulthood and choose our lifelong partnerships wisely, if indeed a lifetime partnership is desired. If not, don't get married. <shrug>
There are many, many more potential calamities involved in maintaining a marriage, in raising a family, in negotiating life, than losing a pile of cash. Certainly losing a pile of cash is one form of tragedy that we ALL hope to avoid- even us old married folks. But if you are avoiding marriage solely because you wish to avoid any risk of losing money, MONEY of all things, then by all means, don't get married.
Ask the spouse who is losing his long time partner to terminal illness, ask the parent who is losing or has lost a child, ask the family whose home and all of their memories have been taken by a wildfire or a tornado or a flood, ask the person who is leaving his or her family to deploy in a war zone, ask the spouse and the kids left behind, ask the person who is being taken from their family too soon by a terminal illness how they feel about that precious nest egg. If the pile of cash looms larger in your mind than any of these potential heartaches, you aren't ready to get married. Peace. There's no shame in that- there's just fact. You may never be "ready" to get married. Peace on that as well, and no shame. The shame comes if you get married in spite of it, and because of it you wreck another person(s) emotional, psychological and/or financial life, and yours as well.
Be honest and forthright about your decision not to marry or otherwise enter into a legal social contract with potential partners. That is basic ethics and will hopefully protect you from creating your own bad karma. If you find yourself involved with a person who hopes to change your mind, do the mature/sane/humane thing and disengage as politely, as firmly, as kindly and as quickly as you can. I say this because it is possible for people to fall in love unilaterally and to project their desires onto the other person. Don't take advantage of this situation; Don't Be That Guy (or Girl.)
Will this honest self-pronouncement limit your dating pool? Absolutely. Grow up and get over it. You do not owe it to any man, any woman, any societal norm or expectation, to your mother, or to anybody else to get married, so don't get married. The people who are dating in hopes of finding a lifetime partner do not owe you their time, their energy, their investment of effort or emotion, nor their physical intimacy, if you cannot or will not fulfill their needs and desires in a reciprocal relationship.
If you are 30 years old and you are afraid that you will not be attracted to your age-peer wife at age 60, and that is your reason for avoiding marriage, for God's sake, DON'T GET MARRIED. We can mitigate a lot of risk factors but science, society and medicine have yet to provide us with an alternative to aging other than death. If you suspect that you may in some manner "leave" your spouse (i.e. abandon part or all of your vows) as your partner ages, a natural process that none of us can avoid, then please, spare any future potential partners that pain. Also please send us all a picture of yourself at age 60 so that we may judge your relative physical attractiveness. (Christ on a cracker I am so glad that my husband does not find me disposable because after 31 years, two kids and menopause I can no longer fit into men's size 28 straight legged Levis. He's happy that I still fit into the kayak, the canoe, my hiking boots, in our camper, on my bicycle seat, and that I can still manage our 80 pound exuberant Labrador Retriever.)
I find it mildly amusing and a bit perplexing that so many young people (men?) on this forum have no problem trusting that precious nest egg to some semi-anonymous or completely anonymous fund manager, broker, financial advisor/service, bank, etc. - a person/entity that doesn't know you from Adam and could not care less about you or your life, is certainly not going to have your baby nor hold your head over the toilet when you are sick to death with food poisoning or a stomach virus, and yet the thought of a SPOUSE sends you into a tail spin. Funny, that.

From where I sit there seem to be more legal remedies available to protect your assets in the face of a failed marriage/pending divorce than there are to protect your assets from a bad investment. Just ask the people who invested with Bernie Madoff. If I'm not mistaken (correct me if I'm wrong) many of Bernie's investors have yet to see a dime from that poor choice.
Also, this thought keeps banging around in that empty cavern above my too wide hips and over-ample middle aged bosom: why are you so very sure that your nest egg, present or future, is an object of envy and desire? Perhaps you need context. If you are so sure that the women (and we do seem to be focused on women as the antagonists in this thread) in your potential dating/mating pool are gold-diggers out to get your money, perhaps you need a good hard critical look in the mirror and at your target dating pool. Unless I am on an internet forum thread with a bevy of 20/30 something Warren Buffets and Bill Gates, I'm willing to bet that there are an equal number of savvy young women out there with nest eggs equal to or larger than yours. Perhaps you are not on their radar, and they are not on yours, because they are out of your league. Perhaps they are keeping themselves out of your way to avoid the risk that you might pose to their hard-earned assets. Just a thought... A little self-improvement and a more enlightened attitude might open up opportunities of which you are not currently aware. A broader perspective may inform you that your groceries ain't all that- and then you could relax a little and simply enjoy your (young) life.
In the meantime- don't get married!