My bank account was closed without notice because of my Coinbase transfers. How can banks do this?

Hi, I live in the US and I banked with a nationwide bank. Last month I received a phone call from my bank asking why I receive so many transfers from Coinbase which I felt was really weird. I told them I trade for a living. Last week my debit card stops working so I call my bank and they tell me I need to come into the branch, I ask to speak with a manager and end up spending most of the day on the phone with my bank. They said they need to update some information about me and my debit card account should be reopen 24-48 hours. I called back every day since and nothing is mentioned about the possibility of my account being closed. Now today I call to check the status and they closed my account because of the “risk factor” how can they do this?? I’ve done nothing wrong. Have you ever heard of anything like this happening and what can I do to prevent in the future? Thanks!