Where do you think all your liquidity comes from when you want to buy or sell some instrument? The difference in price isn't all that substantial if all you do

Where do you think all your liquidity comes from when you want to buy or sell some instrument? The difference in price isn't all that substantial if all you do is buy now, sell when cash is needed in retirement, but if you're that kind of general index investor, one could argue that your contribution to markets is actually negative (whereas HFT is helpful by making prices better and spreads tighter). Buying SPX makes no differentiation between bad and good companies in the index and allocates money based on current prices (which are mainly calculated by HFT's who did the legwork to get to the current point).