"I'm not sure I follow. OP's point is that a failed startup might still be profitable enough to be a lifestyle business."
But who will operate the lifestyle business? The founders and the team?
My point is that the type of person/team that gets involved in wanting and getting into YC (both the founders and the team) don't seem to me to be the type of people that would want to continue in "merely" a lifestyle business. Not that some wouldn't but my speculation is that the majority would not.
From your profile I see that you do LSAT prep.
My guess is that the majority of people who put in the time to get into law school are generally shooting to be lawyers.
If they end up graduating and not getting employment in law (or not being able to sustain that) they might very well end up having to do another job. (Actually they will or they will starve.).
But now we have a case of people who pursue the startup lifestyle presumably for the big win.[1] And now after all the work "all" it turns out to be is "lifestyle" I would think a high percentage of them would then try to get involved in another startup (whether their own or someone elses) not stay and have "only" a lifestyle business.
Otoh if enough time goes on before it becomes apparent that it is only going to be a lifestyle business it's possible that members of the team might have priority changes (marriage and kids) and decide that the lifestyle business is pretty attractive.
[1] Edit: Or to change the world.