Getting them to launch didn't require giving them money however. Looking back, and watching what skills they rely upon now, I can see some (mostly accidental) lessons that have served them well ...
- We taught them to be curious and encouraged them to follow their curiosity. If a kid has no curiosity, it must be really hard for them to figure out what they want study or do for work. We indulged their interests to teach them how one interest (or skill) might lead to another. It's harder than it sounds (like letting dd go to china for a few months at 18 or letting ds use power tools to build things like trebuchets) but it's better than a disconnected teen with no interest in the world.
- Related, we let them grow up early. We didn't baby them until college and then start trying to teach them how to take care of themselves. By high school they were responsible for their own laundry, some family meals, cleaning their own spaces, budgeting for their own activities, and doing some of the grocery shopping. By 18, they weren't too afraid or lazy to live on their own.
- OTOH, we never told them they had to leave. They were helpful, functioning adults by 18 so why would I kick them out?
Two left anyway ... one lived in China until covid and now lives with her fiancé, and the other just moved to Nashville after grad school. The third lives here but only because he works 10 minutes from the house. I think by not making college and career talk such a big 'thing' and flattening out the transition, nerves/emotions never got in the way of what they wanted to do.
I think it's silly that we all live in one or two person households anyway ... wastes money and environmental resources. Plus, I can't kick my kids out after HS and then in my 70s say 'I need help, please come back.' A blended house with an open door policy helps everyone out if done right. I see no reason to run kids off the minute they turn 18.
eta: A recent discussion I had with someone illustrated my point about letting them grow up early and flattening the transition ... His kids are preteens. I told him he should start letting his kids start the car, warm it up, work the controls, do the maintenance, etc. He asked why so early. I said because if the first time a kid sits in the drivers seat is the day of their first driving lesson, there's too much to learn and it's too hard to feel comfortable. Ease them into it and make them feel like drivers before they ever have to drive.