I have been looking at the charts of various markets up to the 1980s. At that time, S&P was still in the hundreds. What I have observed is that the overall volatility seems less (only observation, not quantity). It may affect risk management. Comments?
Before 1980, there was less money, fewer instruments to trade, slower technology available and fewer players in the market. In that sense, things were "different" back then compared to today's environment. Focus on "recent history" instead of "ancient history".
Transactional costs were so much higher. Today is a much better time than back then when costs were much higher. Even if they added this stupid trading tax, back then trades would still cost more.