That's only true if after selling you kept the cash under the mattress. If you sold the SPY S&P 500 ETF in January 1996 and invested the proceeds in the Treasur

That's only true if after selling you kept the cash under the mattress. If you sold the SPY S&P 500 ETF in January 1996 and invested the proceeds in the Treasury-heavy Vanguard Total Bond Market Index fund (there were no bond ETFs back then) you would have seen better entry points waiting for you in the future: 10% discount in Q4 2002 and Q1 2003. 30% discount in Q1 2009