The way I figure it, Peter is not a loser - he's simply not a winner. And by this I do not mean he never wins - the fact that he's survived in his superheroic career this long indicates that he has - I mean that he isn't really winning in life, as it were. That's not because of any defect in his personal character, it's simply a result of 'that old Parker luck'. He's someone who COULD be a winner - he's good-looking, he's highly intelligent, he's easy to get along with, he's even had a book published - but fate keeps tripping him up.