Actually, Harbaugh has been doing a great job and is well worth the money he is paid.
Here is why.
Michigan football annual revenue is $127M. That was in significant jeopardy prior to Harbaugh arriving because the program was averaging seasons of 7-6 under the previous two head coaches and was no longer a top football program. Michigan needed a coach who could turn the program around quickly *and* give an immediate morale boost to the fan base. It was fortunate and a very good business decision to bring in Harbaugh.
Harbaugh took that program, which had a 5-7 season prior to him arriving, and then went 10-3, 10-3, and 8-5. If the 2017 season results had come first in that list rather than last, doubters would have a different opinion.
Also, in the 2016 season of 10-3, those three losses were by 1 point at Iowa, by 3 points in overtime at Ohio State, and by 1 point vs. Florida State (in a year when Florida State was good, ending up ranked #8).
Let's take Saban as a comparison.
His first three seasons at Michigan State as head coach were 6–5–1, 6-6, and 7-5. At LSU, his first three seasons were 8-4, 10-3, and 8-5. At Alabama, his first three seasons were 7-6, 12-2, 14-0. So, yes, at Alabama (but not MSU or LSU), he had a better start than Harbaugh at Michigan. Of course, Saban at Alabama is perhaps the #1 football coach in all of history, so a coach can still be good and not meet that.