The IOC's revenue isn't tax revenue, it's sponsorship revenue[1] Same goes for Team US: as the article itself points out, one of the reasons the US Olympic athletes are so poor is because unlike many other countries the US teams' budget isn't topped up by the tax payer (but is topped up by a bunch of sponsorship salespeople who bring in more money than they get paid but expect close-to-market compensation in return). And yes, like any free market organization, the management and the salespeople are better compensated than the people who are just really, really glad to be there.

If everyone on the IOC executive worked for free without any access to their expense accounts there still would be barely anything left for each individual athlete just for competing, especially if like Team USA their local government wasn't prepared to subsidise things either. So it's really nothing to do with monopoly power either. Olympic athletes are poorly compensated because there are an awful lot of them, and most of them only get a few minutes (sometimes only a few seconds) exposure at the highest level per decade in front of audiences that enjoy watching other sports on a weekly basis

As for the athletes people enjoy watching well enough to know their name and buy their preferred hair gel, the free market means they're compensated pretty well for their brand in individual sponsorship deals. Trouble is, there aren't many Olympians that are household names, especially the ones that really need the money.

[1]sure, local taxpayers often end up underwriting an Olympics after the planners overspend on infrastructure, but that's nothing to do with what goes into the IOC president's expense account, or indeed what the athletes get