They do. It is called a run. Then anything left is bought for next to nothing by a larger bank, and there is then even more opportunity for collusion as there a

They do. It is called a run. Then anything left is bought for next to nothing by a larger bank, and there is then even more opportunity for collusion as there are now less players at the table. It's been going on for a while now and in history seems to be the general trend apart from during those brief times when it is reversed for a while by the invention of new markets and financial technologies. Albeit, this is only my probably wildly inaccurate and hastily sketched opinion.