Mr. Buffett's advice warrants critical scrutiny: it is an unconventionally risky allocation, requires tremendous discipline to avoid investment behavioral traps, and may not allow for sustainable withdrawals in the worst of markets over decades of retirement. One wonders whether he considered his wife's willingness, capacity, and need to take risk. Likewise, has he worked out an Investment Policy Statement with the Trustee where "a terrible period in the market" is defined? Why not rebalance? After a few years, whether markets rise or fall significantly, the 90% S&P 500 index fund allocation will be even higher. Most retirees are interested in reducing volatility, not increasing it.