IMO, greed is the factor here rather than trust (I am not blaming him for being greedy, we all are) as he is trying to portray here by describing FBC as a bank. There has to be some sort of interest (or some promised tokens) which FBC promised, otherwise it does not make any sense to not hold keys to your money.
I also feel sorry for his loss as it is not his mistake, FBC broke the agreement and decided to scam but it will surely serve as an example for future investors.