Good advice. It's easy to get caught up in a comparison with the achievements of others, and to say, "why can't I be like them, why couldn't I have seen that opportunity?" In doing so you make the whole thing competitive - in your mind. The truth is that you aren't them and you probably weren't motivated to try what they did at the time they did it. So why regret it now?
Agree. But let me just add that even if you bothered to try what they did, they could still fail and you could still succeed. Not because of why, but because you were less lucky than them.