If everyone in the world is an equally hard worker, then yes, all success is luck. But that's just not the case. Anecdotally, I knew two identical twins who we

If everyone in the world is an equally hard worker, then yes, all success is luck. But that's just not the case. Anecdotally, I knew two identical twins who were both obese. They both tried to diet, but one always relapsed, while the other got serious and lost weight. Ultimately only one of the twins was "successful" at getting down to a healthy weight, while the other "failed". Is it just luck, then, that one of the twins was born with more mental fortitude? Is that your logic?