For the sake of accuracy, Steve Martin's only NCAA placement was 7th in 1989.
As for the question here, Div I head coaching is now a lot more than getting on the mat and showing moves. Recruiting, alumni relations, fundraising, compliance, as well as coaching and managing a team are all the CEO-like components of major programs. A lot of high school coaches simply aren't prepared or aware of how complex the job is now.
When Maryland's job came open again this past year Debbie Yow's first criteria was a proven Div I head coach. There was a lot of interest shown in the job and she wasn't going to risk her investment in wrestling on an unproven coach.
And yes, most high school coaches who also teach probably do as well or better financially than all but perhaps 25% of the Div I head coaches, without having to deal with all of the experts who take pot shots at them and their programs and the pressure of on-campus issues. Don't forget that there are some coaches who do, or at least have in the past, taught in the local school systems and coached at places like Millersville or, way back in the past, George Washington.