I think it's more important to be satisfied or happy than to leave a legacy. A lot of miserable, messed up people have left legacies and died young, etc. There are many, many tragic cases of famous people.
It's understandable to want to make some impact on the world, and if you want to, you will. However, that may not necessarily mean that you will be Donald Trump...but there are many people who quietly make a tremendous impact on making the world go around every day.
I used to really have issues with wanting to do something "big" and started to feel bad that there was nothing hugely profound that I seemed to be doing with my life...then I realized that to me my personal happiness in daily life (i.e. being where I want to be, doing what I want to) is more important to me than many things, that I'm one of those people who value time more than money. I like being able to own my time, more so than the idea of owning stuff, though stuff is quite nice and money is useful. Also, I realized that I can make an impact on the world by my relationships with other people and simply helping others in small ways whenever I can, because who knows when you could change someone's life by helping them with something that seems small.
But that's just what matters to me, and you'll find what matters to you. I've only recently been able to come into this sort of peace with myself, so I totally relate to what you're saying.