I'm can't say for sure what his rationale was but I could see that he feels that he could do something that NO other QB has ever done, not Elway, Manning, Marino...
That is to win 3 consecutive NCAA championships. He must have a lot of confidence in himself and in his team for him to stay. So these things can happen:
1. He wins another Heisman and wins another championship.
In this scenario, he will still be #1 and will earn even more.
2. He wins the championship, not the Heisman, but still plays well.
3. He wins the championship despite playing less than his ability.
4. Does not win the championship but wins the Heisman.
5. Does not win the championship nor the Heisman but plays well.
Does not hurt him, still a first-round pick.
6. Does not win either and doesnt play as well.
7. Gets hurt.
Drops in the draft but still goes pro.
8. Career ending injury.
Self explaining.
Odds are he will still be fine. Maybe thats his line of thinking. One question though. I am not that huge of a college fan, are there any other QBs that are coming pout next year that are better than him and would be taken before him without question?