Yeah, I don't really understand this. People give me flak for saying it, but I can think of five or so funds off the top of my head (Renaissance included) that I would have happily picked and handily beaten Buffett. I'd make the bet again, today. But like I also always say - Buffett wouldn't have taken that bet up with me, because Buffett doesn't believe in efficient market hypothesis either and is almost certainly aware that individually chosen hedge funds could beat an index fund.
He lost the bet because he chose a fund of funds reflecting the aggregate hedge fund industry; anyone who is even casually familiar with hedge fund returns as an industry wouldn't be surprised at all by the outcome. His choice doesn't even reflect the decision that most rational investors have to make: given a diversified index fund tracking the market and an index composed of the (much smaller) hedge fund market, choosing the latter is silly. A more coherent (and successful) strategy would have been to choose a single fund, or a small basket of funds, known for beating the market for decades at a time. An index fund is a curated portfolio of companies with criteria that make them attractive investments by definition; the fund of hedge funds, in contrast, tracks an industry that mostly doesn't beat the market except for a few outliers.
In other words, the bet didn't really prove anything other than that the hedge fund industry overall is less attractive than the broader market. But I really don't think that was ever up for serious debate among the informed, and now this bet has been modified as a talking point for something it doesn't prove whatsoever: that individual hedge funds are incapable of beating index funds (which is trivially and demonstrably false).