To all "proponents" of "the luck argument": there are thousands of people far more lucky than Elon and Steve (born to wealthier families, smarter, better connected, etc) that didn't achieve what they have. So... luck obviously isn't the answer.
Having said that, even if luck were the answer, I'd still support meritocracy, because it results in the best outcome. It's not about fairness, fundamentally - it's about creating the best society. If the only people who can do that are "the wealthy" (or whichever category you choose - most likely "the intelligent" these days), then so be it - it's best for all the rest of us if they "rule", meritocratically.