Is there some list somewhere of things that people might want? I can build stuff, I just have no ideas.
Also, while I would love to build a SpaceX competitor that mines asteroids, I don't have the capital to chase that. :/
And generally people don't build SpaceX competitors, unless they're already millionaires or have a MBA from Harvard and such. There's a reason Elon started with fintech.
Doing it in the wrong order (selling something, getting customers, then building a product around it) usually results in a bad thing, where you end up giving out $1 of value for $0.80.
There's a lot more details here: https://startupclass.samaltman.com/