Earlier quoted context omitted.
That does nothing to show that it's not down to luck. By your logic, anyone who wins the lottery can claim to be "self made" (since so few other ticket holders had anywhere near the same degree of success).
It is a necessary but not sufficient condition. In determining whether someone is self-made, you'd want to examine conditions like that. That being said, it is absolutely not the case that it "does nothing" to show it's not down to luck. Filtering by that criteria substantially increases the probability of someone being 'self-made'.
Of course it does, because non-successful people by definition can't be "self-made"! (In order to be a self-made millionaire, you have to at least be a millionaire.) What it doesn't do is tell us anything about how much of any given person's success is down to luck.
If you are just going to insist that a majority of successful people (as compared to their peers) are self-made, then you continue to beg the question at issue.