This is pie in the sky but you never know...
If all speculative finance activity were legally required to be conducted on blockchains separate from the base currency - real money might be insulated from risky schemes and the economic crises that result from speculative games being played within the markets. Traders could play their games without putting the rest of the world at risk by being required to use their own cryptocurrency redeemable into base currency but subject to revaluation on the basis of their activites. Irresponsible trading activities would damage the value of the trading token without puting the rest of the economy in jeopardy.
One possible implementation: each trading house legally required to issue a token within which all their speculative transactions are denominated. The redeemable value of that token would depend upon the trustworthiness of their aggregated trades.
I’m not sure if this is realistically feasible - even on a theoretical level (probably not for all trading activity). But I'm posting it just in case it's a good idea...or something that might be built upon by people smarter than I am.