Source? Info I have seen for 2019-20 shows Coyle's total compensation at just under $900K and Barnhart at UK at $1.225M.
Yes, there is a lot of pressure at UK when it comes to basketball. Certainly more tied to hoops there than any single sport at the U. I think that you may be over-estimating how hard it is to survive there, however. They have had three ADs in the last 30+ years and the one short timer was out due to football violations. (By comparison, the U has had eight over that same time frame, not including interims or the women's ADs when the departments were separate.) Not exactly a high turnover rate at UK for the job, so either the expectations aren't as high as you think or the basketball program has been able to meet them.
Agree that he's doing a pretty good job and that he has a high-level of job security. Disagree that the only reason he might leave is that because he hates the people at the U. In the end, it's a personal choice, but you could certainly make the argument that it's a better job.