You could use the same argument for the scammer employee who gambles with your money to make a personal gain. You implicitly consent because you consent to the government prosecuting injustice and returning your misappropriated funds.
Well, not really. Do people consent when politicians reallocate their taxes to bail out too "large to fail" institutions? Given the protests, I think not. What if you didn't vote for the candidate that voted in the bailout? What if you specifically didn't vote (or voted for an opponent of) that policymaker. That's actually anti-consent
The concept of voting includes the possibility that a plurality of voters reject your preference. You consent to this outcome by participating.
When half[1] the population refuses to participate (perhaps they're tired of being lied to, or the candidates are slime, or there are too many selectively-interpreted, arbitrarily-enforced "laws" to count[2], or the idea one person should represent 617,000 is absurd, or they just don't like bossing their neighbors around)...
I believe that people have the opportunity to learn about banks' dealings, which is to an extent mandated by law. This can't be said about the person stealing the funds for their high-risk investment.
Consent is a difficult topic though, I agree. For example, what choice does a person have, not use banks at all? I don't think that's realistic.
Have you ever tried calling your brokerage firm, if you own any stocks or a 401k, to ask them who owns the actual shares you purchased?
$10 says they won't give a straight answer unless you ask just the right question. Eventually you'll find that there isn't a share you own directly, its effectively an IOU claim to a share. People can technically learn how the system works, but that leaves a lot of gray area there.
We could also technically read medical journals and learn how our medications work, but its unreasonable to expect everyone will and recent history has shown that in a pinch you'll be called out for doing your own research and thinking critically.
I'm sure I wouldn't understand their answer, even if they would give it to me 100% truthfully. In fact I just recently learned about the share IOU thing you mention too. And I'm somewhat interested in the topic too, so I too think that people in general understand it even less. Same for medication.