So you were around a few years ago right? When money for mortgages was easy and people were getting houses left and right, damned if they could afford them. The questionable mortgage-backed securities seemed great on paper. People were buying new houses, the market was humming along. Banks, builders, and anyone else involved was making money hand over fist. What could be wrong with MBS then?

In hindsight, the stupidity of bundling crappy loans for speculation was embarrassing, of course, and anyone not benefitting from the game saw the bubble.

If something looks good on paper, but feels wrong , it means we're missing something. In the case of HFT, it's (quite literally) a breath away from insider trading. Insider trading regulations give the impression that the market isn't rigged. If people lose confidence that they can't trust the market, it will fail. The only way markets work is if they're fair and all the players are playing legally.