Online banking scams are one of the most dangerous scams out there. Scammers attempt to gain full control of your online banking, giving them full access to your accounts. They can then transfer the money out in seconds, leaving you with nothing.
Stealing online banking login information is the end goal of many phishing schemes. The scammers who call people claiming to be tech support and asking for access to your computer are trying to do this. They say that they're going to fix your computer, but they're checking your computer for your banking information. Even if you haven't stored this information directly, browser cookies can hold onto this information.
Online banking scams are more difficult to address than credit card scams. When money is transferred out of your account, it could be completely irretrievable. This kind of severe fraud typically leads to investigations with the police and the bank's internal investigation teams.