Solution: regulate the stock market.

Problem: cannot sell things we want to sell.

Solution: Derivatives.

Problem: CDOs cause massive economic damage.

Solution: don't do that.

Problem: cannot sell what we want to.

Solution: Etherium.

...

>Solution: regulate the stock market.

If people want to trade the price of a digital token into bubble territory, that's really their business. No one else is forced to buy up that token. Which governing authority will know it's a bubble anyway? It's not like it's possible to know if something is overvalued. If it were, one could reliably short every bubble and make a profit, and in fact do so so much and at such scale that their market shorting prevents bubbles from ever forming (since a short adds pressure on the sell-side).