Why S&P 500 specifically? Is it just because they have the lowest fees you've found? There are many index funds all over the world to choose from. What if I cou

Why S&P 500 specifically? Is it just because they have the lowest fees you've found? There are many index funds all over the world to choose from. What if I could find a fund with with even lower fees than VTSAX somewhere? I often hear "don't pick stocks, just buy 'the index'" - but you're still picking an index, aren't you?