Fireball is a hell of a drug.
Fireball: Not even once.
You’re talking mad shit for someone in Fireball range
Have you ever seen someone’s brain after prolonged Fireball exposure? Keep that nasty shit away from me!
I now perceive the world in 40 foot radiuses. When I walk into a room I immediately assess the potential xp gain of a fireball. When I choose a table at a restaurant I ensure that I am outside the blast radius of the point any logical wizard would target. When planning my wedding I ensured there would be a counter spell prepared by every member of the wedding party (I distributed enchanted flasks to the martial classes.) My home is a series of right angled hallways and all bedrooms are only accessible by ladder.
I toyed with allowing my players to use the fireball by volume incorrect rule (as it’s not all that well defined in the 3.5 ed we play)
It is as dangerous to the caster as the enemies, especially in a group that neglects to check the ceiling height of dungeons
I like to do this for my veteran players too, after filling the room with explosive gas of course
You keep doing that to older DnD players too, except you drop hints that the enemies are in a cult that has been giving them power and when the wizard does fireball them, the wizard gets hit by a dozen hellish rebukes from all the young warlocks they just hit.
But then you also give them terrain that would allow a clever wizard to position themself such that they can see the epicenter of the fireball without having line of sight to the targets themselves
Honestly, if they caught the hint, understood what it meant, and took action, that would be a miracle and would totally be worth some cheese.