Build where your curiosity survives difficulty

Interest is easy when an idea is new.

The more useful test comes later, when progress is slow, the work becomes repetitive, and the market refuses to cooperate. Does the problem still pull you back?

This is why curiosity matters in company building. It provides a reason to keep examining the problem after excitement has faded. It makes difficulty intellectually alive rather than merely painful.

Passion is often described as intensity. I think endurance is the better signal.

Build in an area where the questions remain interesting even after the answers become inconvenient.