I don't remember half the things I made as a kid but appreciate the "tools" I learned and passion that keep me tinkering.
Like others have said I think that's the real profit to be had.
I'm happy to essentially break even on materials with practically free labor in the few things I've sold. I like how it gets the juices flowing in the brain.
I've never felt guilty in spending money on tools that'll keep your creativity up. It's very satisfying. Go for it. It's not like there's a bunch of capital expense involved.