A painting is never finished. You just stop working on it.” This idea will be familiar to anyone who has worked on software. - Paul Graham

Focus, as Steve Jobs said, is about saying no.

The only dangerous competitors are focused ones.

Ergo there are things that even the most dangerous competitors say no to, and it would be worth thinking explicitly about what those are.

Don't fear competitors who've raised a lot, unless you can say precisely how all that extra money is going to make them beat you. E.g. if ads are the only way to acquire users, and they can buy all the ads, you're in trouble. But money per se is not dangerous.

Someone trying to live well would seem eccentrically abstemious in most of the US. That phenomenon is only going to become more pronounced. You can probably take it as a rule of thumb from now on that if people don't think you're weird, you're living badly.