Are you serious? You're saying it's balanced because at level 17 my cantrip is doing 4d10? Really?
Alright, you want to compare endgame, aka the levels that less than 1% of the playerbase will ever experience? Let's do math funtime!
Sorcerer Fire Bolt at 20: 4d10+5 = 27! And you can twin it up to 20 times I guess, so 8d10+10 = 54
Barbarian Raging Reckless Swing at 20: 2d12 + 14 (STR) + 8 (Rage) = 35 minimum with a higher chance to hit. If he drops a creature thanks to GWM, he can take a bonus action swing, so 3d12 + 21 + 12 = 52.5 . Ah, but if he crits, thanks to Brutal Critical and double crit chance due to that on-demand advantage, it's 6d12 + 21 + 12 = 72.
This is ignoring that -5/+10 still, of course. Otherwise bump the minimum damage to 55, then bonus swing to 82.5, and the one crit bonus swing to 102.
Ah yesssss, my cantrips at theoretical endgame is soooo good. Balance!
Yes, of course, I do get other nifty things. I readily admit that. Not many though! It's that gosh darn "I-only-have-15-spells-total-ever" problem. Contrary to popular belief, the sorcerer is NOT a wizard!
Want to see my spells at level 7?
These are my current spells. I got my blasting spells, I got Shield because I don't have D12 HP, then for my "nifty stuff" it's Disguise Self, Fly, Greater Invis. Polymorph is my overpowered spell! Note how many times I can cast these spells, up there in the top right.
Take away from the barbarian? Have you seen them in action? I have. In every playgroup, even. They are the action. They are in the frontlines, shrugging off hits that would KO me, and dealing consistent huge damage. All I ever wanted was to be the glass cannon, the Black Mage, that can outpewpew when needed. And now it's stuck on Fireball or bust.