I acknowledge that they could indeed be that successful, but I still maintain that I have no reason to believe their claims until they provide me with something more solid than that ad.
Perhaps I have more faith in PG's judgement than I ought, but that strikes me as excessively cynical.
I'm guessing you didn't like the post (note, it's not really an 'ad' as you stated) for some reason and are coloring the entirety of their claims with the same brush.
I'm guessing that, bravado aside (and I didn't personally find anything particularly braggadocious in the post to take offense to,) I would wager real money that their claims were at least truthful.
No. Rather, I have no information that I trust to convince me one way or the other as to their honesty, so I choose to ignore that data.
I had not, however, considered that they have already been vetted by PG and YC. Perhaps I have a small reason to trust their claims. Even so, I'd give it the same weight in decision making as known hyperbole, at best. I'll only completely trust the claim if I have verifiable sources.