Seems like you thought the same about YC: that they'd do the vetting for you. And yet you're set on making the same mistake again by relying on someone else to do the vetting.
Almost every start-up is a huge gamble. Naturally, the later stage you join it, the lower the general risk. In that case, why stop at Series A? If risk is all you care about(and it sure sounds like it from your post), why not just join profitable companies that are no longer startups? Much lower risk, promise.