I suppose any HC can decide that making $1.5 to $2 million more in compensation for the 2018-2019 season than he is right now isn't worth it. But would surmise that most coaches - especially those below the P5 + 1 level - that have an opportunity to cash in would not take that approach. However it's up to the individual.
Any college HC that is interested in ascending to the top level group of HC's in terms of compensation has to determine their value right now as compared to where it could be headed: up or down. For some, their stock may well be higher right now than it would be for the next several years. Or ever. A lot can depend on the roster that is coming back and how many key pieces will be leaving. A bad season or 2 can derail plans.
In Hurley's case, he may well be content to stay as the big fish in the little pond. If he does, he'll be compensated relative to that. Maybe he'll have another chance to make a millio (or millions) a year more?Maybe he won't.