I don't think market values are the issue here. It's just the level of these salaries -- totally out of line for a non-profit institution. This house of cards is about to implode.
What people are missing is the NON-Profit doesn't mean the organizations do not make money, in some cases ridiculous sums of money. There are quite a few non-profits who pay their CEO over $2Million
The misnomer here is "non-profit." Instead, these are "not-for-profit" ventures, which means they aren't INTENDED to make a profit. In the '80s and '90s I worked for a not-for-profit trade association that made bundles of money each year through its annual trade show, which was one of the largest in the country. They earned a tidy profit, a good chunk of which went for exec bonuses, and even the underlings got nice bonuses because for most their regular pay was tied to wage rates for similar federal jobs, which usually lag behind private sector pay for the same jobs. There was usually some left over at the end of the year, and there were limits on what could be earned through such side activities. But so long as it was funneled back into the organization for equipment, etc., the IRS never raised questions.