Its interesting, I never really thought about it like this. In high school I was an extreme procrastinator. Avoiding the boredom of doing the task is certainly part of it, everything was too easy. But when I know I can finish an assignment in two hours the night before its due, why would I ever start it early? There was no benefit to completing things early. But, there was always a high from getting away with procrastinating to the last minute. Just like that rush from solving a hard programming problem. Essentially I experienced a reward for procrastinating, and was always chasing that. At least that is how it felt to me.
But eventually, after some time not doing so well at college because of this, I ended up joining the Marine Corps. Since then, I have been much less of a procrastinator. Not really because my motivation or anything changed, its entirely because my tolerance for uncomfortable situations and tasks went way way up. So this explanation actually makes sense to me once I really consider it.
I had the same high school - college experience as you. HS was easy to pull off with no work and last minute efforts. Then it caught up with me in college. Instead of the Marines, I did a restart at a lesser college, and ended up becoming friends with a group of dudes who had had the same exact experience. I think part of it is related to the growth/fixed mindset theory.
But eventually, after some time not doing so well at college because of this, I ended up joining the Marine Corps. Since then, I have been much less of a procrastinator. Not really because my motivation or anything changed, its entirely because my tolerance for uncomfortable situations and tasks went way way up. So this explanation actually makes sense to me once I really consider it.