I went and had a quick look and salaries are relatively low at maybe £50k, compared with a partner GP at maybe £90k+. One the other hand, a GP works 48 weeks a year, while a don teaches for just 24 weeks a year, which balances things up.
In any case, it's a free market - if people really want to be accountants no-one forces them to be dons. I think the current discontent is that dons used to be able to do pretty much what they liked, while now there's increasing interference and bureacracy in the job.