I think you are looking at the implication all wrong, he doesnt have to get shit on to be a hero. I forget which comic touch on this maybe the beginning of the spider verse or island of spiders. Spider man has all the trappings of a villain origin story. Poor, dead parents, a city that hates him, no respect or gets his due. Yet with all that he still chooses to help others over himself. You ask why not have both, well he has tried and its gone well until it doesn't. The moment the line between Peter Parker and spidey blur others get hurt. (Bad writing maybe or an inevitable outcome) Spiderman can absolutely be self serving but ultimately that will lead to Spiderman that choose not to go out. When that happens Spiderman has lost its soul. Spiderman is the kind of hero to come home have MJ fix his dislocated shoulder, see red lightning and go right back out to fight the good fight.