, but maybe also having it be successful enough that it opens the door for another book.

Unlikely. And that's the point. That's okay. To not get to that level is the norm. There's no sense fearing the obvious, the typical, the usual. Again, worst case you end up where you started (had you done nothing).

It's like traveling isn't it? Eventually you end up back at home (i.e., where you started) and yet you're damn happy you left. So yeah, pull the handle on the slot machine and let the chips fall where they may. No reason to be afraid.