“Buffett recommends putting 90% in an S&P 500 index fund.”
well, i suppose that’s all well and good, but that is NOT how Buffet made HIS fortune ... an even BETTER investment approach followed by many was simply to buy Berkshire Hathaway shares and hold them ...
For the past 3 and 5 years SPY has beaten BRK.A.
To be fair, in 2021 BRK.A was slightly ahead of SPY, but did not overcome the underperformance of previous years.
While buying BRK.A has been good to many investors, and is not a bad strategy, I have refrained from holding any. Ask yourself what do you think will happen to the price of BRK.A when Warren Buffett shuffles off this mortal coil? He was born in 1930 and is not going to live forever.