Newbie player doesn't know how to play DnD and keeps bashing the system
Hello all, I need clarification if I am overreacting on this. I am a veteran player that played a LOT of table top RPG's (only DnD™ 5e) and currently am in a lvl 6 table with a new player, let's call him John. The problem is, how doesn't know how ttrpgs works so far.
Last session he was complaining that his martial is boring to play and that his only option is to just attack and that Dnd™ 5e is a bad rpg system. I thought this was quite offensive against my favorite system, but I calmly told him to shut the fuck up and that no one's forcing him to attack every fucking turn. Like, doesn't understand by now that DnD™ 5e is a brilliantly designed system that lets you do LITERALLY anything???? (Well, you can't exchange your extra movement for a bonus action, but that's besides the point). Instead of asking for the DM for some chandeliers to swing on, he then continued to whine, replying that not attacking was "being useless and not helping the team", but I let that pass this time.
But here's when things started to get heated. On a dungeon fighting the first BBEG, I single-handedly ended the encounter in two turns with my homebrewed caster that consistently deals 60+ damage per round. Instead of thanking me, John started to cry again about "muh balance" saying that is not fair that I can "literally bend reality and the laws of physics" while his dumb martial can't. Like duuuuuuh you picked a martial in DnD™ 5e, only casters can do cool stuff!!!. Also, he shouldn't be blaming me for breaking optimizing when the DM is not doing his part with balancing the game, like adding 10 boring encounters per day like the DMG ingeniously suggests or fudging the enemies HP or making the enemies focusing solely me or giving every single enemy Legendary resistances. But no, he continued to complain and before rage quitting the discord group he said something about playing a system called "Wayfinder" or something (Idk I only play DnD™ 5e).
I know no DnD is better than bad DnD, but do you guys think I should I forgive this guy and invite him back to our table? How do you guys say?