I know we all hate Elsevier, and I do, too. But the assumption in this threat that one could get rid of publishers without any thought and with absolutely no downside is simplifying it slightly too far. Elsevier currently has a margin of about 35%. That's a lot, and probably too much. But it also means they are spending 65% of revenue on something . Even assuming a decent chunk is marketing and sales, there are a few…
There's no way to support your reasoning on even roughly estimating their costs by bootstrap deduction, without more information.
Maybe a single person could have compensation valued at 100 million dollars. Yes, it happens not to founders but to employees.
Cost of sales at a large revenue company like this is usually very high. Top performing sales people are extremely well compensated.
It's possible you've guessed correctly, I'm just saying there no reason to assume it's even roughly accurate from your premise.
The bottom line is their very existence go against the concept of maximizing shared scientific knowledge.
They also apparently consider unethical smear campaigns a standard business tactic.