Most likely, Manziel is going to excel and make a lot of people look dumb for doubting him over his antics and unconventional ways. If anyone is curious about Pete Carroll's opinion, he thinks Manziel will be a terrific QB and says people should be more open-minded about his unique qualities and personality traits. But hey, what does Pete Carroll know anyway.
Of course, if Manziel DOES fail, and even the best can fail, then he's going to accompany Ryan Leaf in the NFL draft bust lexicon. All the crazy stuff he's done is going to fit very nicely on an epitaph.
I think he knows that, he's a bright guy. That he does all this stuff anyway and effectively "doubles down" I think shows just how confident he is. Too confident? Probably. But I'd rather have a QB who is too confident than one who doubts himself.