That _earned_ thing is subjective, and this is thoroughly made fun of in One Punch Man. E
Some fans on the other hand, thinks that YES, he earned that, because he's trained his ass off and we WATCHED him train and struggle, so we find connection with him--when really, Saitama's growth is just some bullshit. But it's a comedy manga so eh. May not count.
Point is: I get what you mean. I really do. What you don't get, is why I also enjoy bullshit powerup, if they provide me with catharsis.
I'd watch a bully who's been bullying a kid for weeks get beat up kid the next day by the bullied kid and I wont even bother asking where he got that stick and if he's trained to use it before.
Get what I mean?