You are forgetting that that contract was not signed until after the 2020 season, and that was after he had been with NU as HC for 15 years and during that 15 years he had had numerous opportunities to go elsewhere but showed loyalty to NU. He had just had 5 of 6 BIG winning seasons. We had just gone to a second BIG Championship game in 3 years and also with the win over Auburn had gone to bowl games in 5 of 6 years and had won 4 straight bowl games so 2019 looked like an aberration. He had numerous potential suitors at that point including NFL teams, He was 25 games over 500 and even had a winning record in the BIG. And that was at NU with all the constraints that other programs did not have to deal with.
Like it or not, he had earned that contract and at that point, no need to look elsewhere. You can argue that it was longer than it needed to be but it was understandable given the circumstances and you cannot argue that he did not earn a contract extension. His first two years under that contract were disappointing. He had made a bad hire and some of the QBs we had counted on had not worked out, But after that second season, he corrected his mistakes and it looked like he again had set up the program for success