Well, they probably don't want you removing money from the account to invest in bitcoins... because they are already using your money to invest in bitcoins, but for their benefit
Good old banksters.
It is insanity. As one of the absolute fucking idiots that bought $40 worth of bitcoins back in the day and sold it because I didn't think they would be worth anything, you never know if this is still in the infant stages or if it's peaked already.