Non-accredited investors don't legally have access to leveraged trading in the US -- many were using it illegally and/or violating ToS of various exchanges. But

Non-accredited investors don't legally have access to leveraged trading in the US -- many were using it illegally and/or violating ToS of various exchanges. But overall, leverage was not what caused the bubble or the majority of the losses. The fact of the matter is that trading is mostly a zero sum game, and your typical emotional, uneducated retail 'investor' doesn't stand much chance of scalping a substantial profit from people and organizations who are either A. long term investors that bought very cheap and unloaded during huge rallies and more so B. professional traders that provide liquidity for the market and make extra money when retail emotion and high volume increase volatility. You could ban casinos, the lottery system, as well as a number of economically necessities such as credit cards, publicly traded market systems, etc., and you STILL would be unable to protect some people from their own poor financial decisions. So I say, as long as fraud in these markets is punished and disincentivized, there isn't much more to be done.