Miles has good intentions, but has destroyed a universe through his actions (following Gwen and saving Singh), this was fair because he was not yet aware. After Miguel explains to him the danger of messing with canon events, Miles is determined to save his father. I'm sorry, but I believe in the sacrifice of one for the many and not the other way around. If he tries to save his father in the upcoming movie, everyone else could die.

I suppose another small thing that stuck with me (and generally sticks with me, now that I'm older, though I used to relate at a younger age which makes sense) is how Miles insists he's not a kid and 'basically an adult' because he's 15. Hun, you are still a kid and that's okay! Kids make mistakes but on a universal/multiversal scale you absolutely NEED to listen to the grown-ups. You are risking billions of lives.

Attack me, but it might be difficult to change my mind.