the equal-weight guy since '03 has beat the SPY guy by 0.53%/year.

Since '03? Firstly, how many investors bought RSP right when it first launched in April 2003? Most investors wait until an ETF has at least a full 3-year performance history before buying. I know I would. So a first buy in 2007 is far more realistic. Let's see how that investor did.

The below results will come as a shock to most of you, so let me break the news to you gently. The RSP investor actually suffered a greater drawdown and greater volatility compared to the SPY investor. And for what? For a lower annualized return of 8.7% compared to 9.2% for the market index.

If you were counting on equal-weight to be less risky during severe market downturns, you were in for a rude awakening. RSP was down 55% during the Great Recession compared to 50% for SPY. RSP also declined worse than SPY during the Covid bear market of 2020. And during the bear market of 2022, RSP declined almost 30% compared to 27.5%. So RSP provided no protection and actually performed worse during bear markets. It's also been more volatile, as shown below.

SPY vs RSP since 2007
                       SPY     RSP
Annual return (CAGR)   9.2%    8.7%
Volatility (GSD)      15.9%   18.2%
Max drawdown (MDD)   -50.8%  -55.6%

Secondly, RSP is not generally available in tax-deferred 401K plans. So you have to include the effects of taxes on the dividends. The 401K investor doesn't have to pay taxes on a Vanguard S&P 500 index fund. Also, the RSP ETF's expense ratio is 0.2%, which is 5 times the expense ratio of the index fund. The taxes and the expense ratio for RSP add up to more friction.