They already have exactly this issue (not that I think it's a big problem), if you apply to YC and convince them you want to build the next Slack, but in realit

They already have exactly this issue (not that I think it's a big problem), if you apply to YC and convince them you want to build the next Slack, but in reality you just want a comfortable life for a few months, that's entirely possible already. But since their entire business model is based on them being able to evaluate people, they probably don't think the risk of this kind of deception is too high. And I am sure they wouldn't sue you for it.