Many breaches are inherently more efficient than litigation, where the only winners are often the hired attorneys. In some cases, it pays to litigate. In this case, spitballing numbers, let's say that Miami offered Mensah $1-2M more for his services. IIRC, Duke was paying him $4M, but let's use that figure. Miami, Duke and Mensah may have agreed to split the difference, and Duke walked away with an additional 0.5-1M in the deal, and still have the $4M in NIL they were going to pay Mensah. That's a win win, versus spending over $1M or more in legal fees, witness fees, court costs, travel, the uncertainty of who would win, etc. In my practice, I tell clients I'm a make love not war counsel. I don't litigate. I did litigation for a while, but I enjoy more building versus fighting and/or destroying. But litigation can be a terrific rush and rewarding if you don't mind giving up more of your personal life compared to doing transactional work.
As for your last paragraph, there is a sucker born every minute willing to sign a contract for $$$.