You can't just decide what you want to accept or not. Gravity is something that exists no matter how hard you try to fly. You'll get around it, build airplanes, ask your little friend with the floating quirk for help, but it doesn't take away gravity.

[He points at Izuku for emphasis.] I'm not telling you to give up! I'm telling you that I couldn't save everyone, and neither can you. Learn that lesson now before it hurts you later.

[He drops his hand.] Do everything you can to keep them safe, but be ready to make difficult decisions, if it comes down to it.