I agree. For example, I can think of creative people that have been successful that just produced what they loved, without a customer in mind. If they had started off by thinking “how can I optimize for theoretical customer X?”, they never would’ve been as successful.

Don’t make a product for others. Make one for yourself that you can dogfood. If you can’t do that, you’re on shaky ground.

Your first customer is always you. If you don't have a problem to solve that you know something about, you aren't going to make a useful product. A useful product can be a successful product.

Absolutely, must be problem centric and problem obsessed.

The value of the problem being solved is what attracts and retains users.