The operations fee required for that company posited to have just raised its series A to park its fat stacks of cash is going to be negligible (as it should be constant for any size of account).
Well the other side of the equation is it would be very very tempting to do something with all that cash. Like “let’s fire the CEO who doesn’t go for it” tempting. I don’t see this working without regulation.
The problem for the startup is they are already doing something super risky and so want to be 100% conservative with the cash used to finance their operations. The last thing their investors want to hear is "so yeah, you wanted us to shoot for the moon with your money, but we didn't want to lose out on a couple percent of interest so we invested it in the market and that's down 20% right now so we're having to wait a bit to execute part of our strategy as we expect that to go back up soon".
Like, the problem is that the mental model of this money is wrong: there needs to be a place where a company that intends to take a bunch of money in and then spend it over the course of a few years can do that without it causing everyone a bunch of issues as those deposits were supposedly backing loans to still other people (such as that story with the hashicorp people that was posted here yesterday with the Chase bank branch that failed to understand that a startup's goal is to lose money, not invest it).
