Markets are inherently unstable,* run as they are on whim and panic. Every time there's a country-shaking implosion, laws are put in place to control the worst swings downward. Trouble is, said laws also tend to slightly impede upward swings as well, even where government policy is not actively counterproductive^†; so the lobbyists push to have the safeguards relaxed because "it'll be different *this* time". Surprise: it won't be.

* The techie in me keeps saying "chaotic relaxation oscillator".

† But that's a different argument, which need not detain us here.