First of all title of your topic is misleading ad it says Bitcoin is dangerous for economy and later you says banks intervention is dangerous so they are contradictory to each other.Some banks are providing crypto related services to clients such as buying and selling Bitcoin on your behalf but that's do not harm your economy but this also doesn't implies that bank will provide your safety of the funds.They will just take comission for providing services and use your funds to make transactions so it's better to have control of your Wallets in your hands and trade them efficiently.Banks should only allow to process your crypto transaction from your account.But there is nothing that will harm the economy as many major banks are doing this so they will not take any decision against their country.This is source of revenue for them.