I've visited 14 countries (lived in 3 different ones) and 10+ US states (lived in 3) and I can count the number of plane/boat tickets I've ever paid for myself on one hand. My sister has similar numbers/states. Different means but same ends. Of course, it's not about quantity but quality. Lets just say both of us have spent a significant amount of our lives "abroad".
In my case, it's been a combination of academic conference travel and being willing and capable of relocating for new work. The job would typically pay both for the travel (+per diem) as well as the relocation. Relocation is also partially tax deductible. Relocating both saves the money from maintaining two homes; traveling as part of work whether it's for a 1 week conference, a 5 week research visit, or a 3 year posting makes it possible to embed yourself in the local culture compared to brief visits. You will know the names of your neighbors. You'll join a sportsclub or some other club. You'll make friends. You'll pay taxes. You'll understand the work-culture. Also the politics. And you'll get to see your own country with foreign eyes.
For my sister, it was volunteering or getting paid room/board/stipend for 6-12 month periods as a teacher, vineyard farmer (wwoof style), nanny, au pair, waitress, etc. Sometimes they'd pay for the travel too. Otherwise, same idea. Lots of places around the world who are eager to exploit cheap labor for lifetime experiences. She daisy-chained all this together and spent some 10-15 years (20s and early 30s) traveling almost full time depending on how you count (sometimes she returned home to take a university semester .. or to work for 3 months to replenish the travel purse to buy the ticket for the next adventure).
So,
Travel-hack #1:
Making it a lifestyle costs much less than buying it as a product.
For something like short-term tourism, I would second the import-export idea above. The destination country might have a few things that are really cheap compared to the home country. In that case, buy stuff and sell it when you get home. Or if you really need/want something, you can buy it for yourself. The cash-flow analysis will be less convincing though; but you can always think of it as a souvenir.
Add: One of my (older) cousins was a flight attendant for several years. I remember her telling me the reason was that it was a way to see a lot of the world. I was too young to appreciate it at the time. (Maybe this whole travel-while-getting-paid gene runs in the family.)