A 22btc ask wall is child's play for even a whale calf. The whale takes out a couple ask walls and puts up a healthy bid wall at 6 or 7 and a lot of silly amateur gordon gecko wannabes are going to be sad. Maybe the exchange gets hacked or closes up shop and just decides to keep everyone's coins...think we've all seen that play out a couple times now.
I think we will only see that when sell side pressure at 5 subsides and volume goes down. If I had hundreds of BTC and was in the stage of accumulation, that's what I would do. At the moment, plenty of sell side pressure at 5, but not very much at 4. So that's the perfect place to accumulate right now if you had a lot of BTC.
But yea, exchange shutdown risk (also known is counter-party risk), is definitely very real. If regulation was ever needed, it would be for how exchanges are run. Unfortunately this regulation would come at the price of governments using these exchanges to try to catch crooks, which means they would demand our ID information, which then puts the consumer at risk of identity theft. Then it's only a matter of time before the American IRS bursts in demanding the information in order to go after tax evaders, and of course this can be done in a way that selectively targets people of one political persuasion or another depending on who's in power. =/
I want to be able to comply with the law, but I want it to be easy and cost effective to comply with the law too!! Sadly it's the 2nd part that regulators never get. Or perhaps they do, and they make it over complicated and expensive so that the legal firm these regulators happen to own gets extra income on the side. I mean what better legal firm to go with than the one that actually wrote the rules, right?
*face palm*
For all the BS and artificial costs this society imposes on us, the TZM as envisioned by the movies only moves the regulatory powers from bureaucratic types to the computer programmers. A improvement over the previous system maybe, but still the potential that someone will abuse their power eventually. Thus the need to decentralize, decentralize, decentralize, and prevent any small group of people from ever attaining too much power. =/