You want to sound crazy, but you want to actually be right.
Whatever the founder cares about, whatever the founders think are the key goals, that's going to be what the whole company focusses on.
In YC's case, the number one cause of early death for startups is cofounder blowups.
You'll get more support on a hard, important, project than a derivative one.
The natural state of a start-up is to die; most start-ups require multiple miracles in their early days to escape this fate.
Here's a good rule of thumb: don't worry about a competitor at all, until they're actually beating you with a real shipped product.