> Factor in inflation and its pretty easy to get negative returns on bank deposits.

But that applies to having money at all. That can't be enough to call it gambling.

> expectation, intent

I understand your argument here, but I disagree. Shifting to the bank that offers the best rate is good management, not gambling. Understanding how interest works and being motivated by interest to do bog-standard money storage doesn't turn that storage into gambling.

> without doing anything else

I don't understand how this connects at all. Maybe it reflects badly on you if you want to turn money into free income, but that doesn't make it any more or less of a gamble. It's a totally different axis.