I don't think you understand that people who make markets (add liquidity) decrease YOUR investment costs. These market makers can only trade millions of shares

I don't think you understand that people who make markets (add liquidity) decrease YOUR investment costs. These market makers can only trade millions of shares per second (a vast overstatement) IF there is actual demand for that. Suppose there is such demand. Then, the market makers are providing a valuable service by supplying liquidity for people who want to buy or sell. A sales tax would vastly increase costs for everyone involved. Your parents pension fund would generate lesser returns because it costs them more to enter and exit positions. Your "back to basics" quip is bullshit. What does "going back to basics" even mean? People trade because they think they can make a profit or hedge their risk. That's all there is to it, nothing "more basic".