[make_it_sure]

Exactly. I started building stuff at 17 and found "the one" (doing over 1 mil/year) at 27. I can't count how many failed projects I had.

[jalapenos]

How did you identify your ultimately successful niche, and what do you feel was different about it than your previous attempts?

[drpancake]

When you know you know. It's like the difference between pushing a boulder uphill and downhill. Very hard to predict ahead of time - you just have to keep shipping stuff.