“...derivatives sometimes of dubious value being used as collateral and guys betting on this or that to go up or down how is it different from big time gambling?”
It isn’t different from big time gambling. You have heard the phrase, “no risk, no reward”? If steps were taken to remove risk from the markets on equities, etc the returns would resemble what we are now seeing on Treasuries which are guaranteed.
No one should ever put money into the stock market that they cannot either afford to lose or will need in the next 5 yrs. The time frame is critical since except in very, very rare occasions the value of an equity will always return to where it was over time. Of course if forced to sell at the post crash price the money is gone.