A single mediocre hire in the first five will often in fact kill a startup.
There's no way I know, to get through the pain of a startup without belief that the mission really matters.
Unfortunately the trick to great execution is to say no a lot.
At the beginning, you should only hire when you have a desperate need to.
If you compromise and hire someone mediocre you will always regret it.
... the thing we see wrong with YC apps most frequently, is that people have not thought about the market first and what people want first.