On the off chance that said friend does happen to succeed then I am willing to apologize for being skeptical and learn from the experience.
But why? You have every right to be skeptical, and even if he succeeded (by the way, it would take years to even know if he succeeded because like I said he could get money once but it definitely won't last) you have no reason to apologize for being skeptical. You don't have to learn from this experience because it's such a one in a million shot that if another friend came up and said the same thing you shouldn't go "well this guy did it, i guess i shouldn't be skeptical", because chances are that second friend isn't going to succeed at that same one-in-a-million shot! It's not a matter of becoming wiser, it's just dumb luck and that doesn't make you wrong to have said it was such a bad idea.
Actually there is pretty much a ZERO percent chance this could be his career because it won't be long before it's some completely different game that all these tournaments are based around, and unless you're that autistic kid from The Wizard you aren't going to suddenly become a top player in it too. If suddenly no one was playing football, it's not like the football players could just immediately pick up basketball.