> for every successful person, there are countless others born to a similar level of privilege who squandered it.

Indeed.

> The claim that everyone owes their successes to the group ignores this.

This doesn't follow. Can you elaborate?

By "owe" I mean that the credit for their success belongs to the group and not the individual, because the individual was merely a product of good circumstances provided by the group. I believe this is the sentiment intended by the "no such thing as a self made man" crowd--no individual is special, and anyone else would achieve the similar things under similar circumstances. This ignores the fact that many others DO enjoy similar circumstances but achieve nothing.