We all think these people are over-paid.
It is a market, but BBC should not spend public money to support it.

If they refused to pay such fees, the market would at least fall a bit.

Would we care if shows that rely on big names were mainly found on independent stations?
They are not the shows BBC is most valued for.

Sales people have an advertising budget, and it makes no difference to prices how they spend it.
It would make a difference to the licence fee if BBC paid less.