It's very important to not over-fixate on your toe hold.

Your toe hold is the thing that gives you "grip" and allows you to create momentum to rally around.

If you optimize too much for that niche you'll inadvertently create something that only works for that niche and increasingly doesn't work outside of it.

Getting to a toehold (bootstrapping a feedback loop) is everything, and yet make sure that any specific toehold you find doesn't become your everything.