The tale of Straddy - A DM who wants in on everything.

I'm a fairly new TTRPG player, and so far, I've only played D&D. My best friend dragged me into it sometime in May, inviting me for a session, so I could come and watch. I "played" D&D before, but to be totally honest, it was horribly unserious, and my party tried one session, and quit.

But now, with a second chance at the game, i met my current party, and from now on I will be referring to them by their game names. Zolar, Peakwatcher, Johnquest, Ram and Straddy.

Ram and Straddy are both DM's in their individual campaigns.
Ram's campaign, which is the boiling pot of this story is a fully custom homebrew adventure titled "Hunt for Hyperion" or "Hyperion" for short.
Straddy's, as nobody expected !, is "Curse of Strahd" albeit heavilly modified with Warhammer, especially Chaos Gods (Slaanesh and Tzeench...mostly Slaanesh).
When i first joined, i really thought of Straddy as a good DM, but with every next session, the image started to shatter. To start, he was a GIANT buzzkill. We all like a little chaos in our game, yet he became agitated whenever we wanted a laugh. Second of all, he put way too many Chaos-related stuff into the game. Yes, Warhammer is transferable to DnD, but it's Curse of STRAHD, not Curse of Slaanesh, and I'm saying it as a person, who really likes the Chaos Gods, Slaanesh especially. It was my mistake to choose a Slaaneshi character, as now Straddy does not allow me to make ANY personal changes to them, as he "grew attached" and he "favors them", his words exactly. Straddy made a custom adventure for us in the CoS universe, where we faced our worst nightmares (mind you, only me and Straddy are into Warhammer)
and of course, each character's dream was Chaos related. Zolar, canonically has a bond with my character, Yllusio, as a somewhat adoptive sister, and only by this, Straddy inculded her in my nightmare, giving her as much individuality as the fact, she woke up in her temple.
Feeling adventurous and creative, i wanted to DM a short portion of the adventure, giving Zolar a custom nightmare she deserved. Straddy insisted on DMing it, even though I've done all the work, and got huge support from the other players.
Ending Straddy's offences in his own campaign, he would often disregard his own work, and not warn Ram, who could prepare his own content, until the final moments, which often made Ram miss a few hours of sleep, and given he lives on the opposite side of the city, commute is hard, especially on Sundays, when we usually meet, and he often overslept, coming in late. Not much, but still.

Onto Hyperion.
Hunt For Hyperion is a fully custom campaign, though heavilly inspired by a few universes bashed together, some including "Laika" "Titanfall" "World of Tanks" and "Accelracers".
Straddy, now a player, wasn't a huge fan of HFH from the start. He made a character, which he said, he likes, just to whine that "he is tired of playing them" one session later.
Somehow, as if the world intended us to, we all roll kind of bad in this campaign.
This results in minor irritation and laughs most of the time, as of course, there's epic moments too. I, myself, really love the campaign....But Straddy doesn't.
My character, Spitz, was originally a kobold, but i discussed a big plot hook with the DM, and he was revealed to be a warforged in the latest bossfight.
Why am i mentioning this ? See, the fight was like a match thrown into an open gas tank.
This fight was a truly unique experience, as it was out first actual boss, which also was a big part of the lore. This, of course, meant that it couldn't be a forgettable battle, in which the "Lesser-BEG" takes three hits and, like magic, passes. And that's what Straddy hated....
You see, Straddy's approach to bosses is...very mediocre. It feels like they just...exist.
Ram's fights actually feel like a part of the story, and not a metagamer feeding pit.
Straddy complained about HFH before, but truth be told, it mostly just made us roll our eyes and sigh. This time, though, was different.
The bossfight lasted for about 1,5 sessions, which is quite long, and Ram himself admitted he missed some points here and there that would make it more concise, but nobody seemed to care, as we all had a great time. Or, so we thought.
Straddy insisted on writing content for his session during the game. For me ? It was already extremely rude and diminishing towards Ram. It's one thing, when someone's on their phone, or chatting to their "seatmate" during session, but it's another, when a DM says, with clear intention, that he is going to focus on his own stuff. He whined about everything.
The fight, the layout, our moves, truly, everything. He, himself, was no help at all.
Oh...i almost forgot to mention. Whatever we tried telling him before, he dismissed as "A rookie DM mistake" and tried making himself look like a pro, forgiving an apprentice for messing somethning up.
After what felt like him getting more and more angry with every turn and failed throw, like a child, getting told "no" repeatedly, he finally got up and said the exact words. Well..not exact, but i'll translate them from Polish as closely as I can.
"You know what ? If we just come here to sit around and do nothing, why are we playing this game ?"
I snapped. I went up right to his face and told him off. Pretty severely.
I went off about how he thinks a big plot hook and a great villain are just "sitting around", ad if he never battled before. I told him we're all sick of his complaining, that the campaign is not his to change or lead, and that what he did, was fucking uncool.
He was pretty shocked to see someone "bare their teeth" as Ram later called it, and again, tried to make himself look like the better person. When it died down, we continued with the session, and Straddy finally rolled something good. A Nat 20. And he celebrated it like Tzeench himself aided him to it. And THAT was the best part of the whole session to him.
We had a big reveal, we had several cinematic moments, we had Roleplay..nope, the best part was him rolling a Nat20...on a non-combat throw.
Even when we were leaving, he went on about Ram being a "Rookie" and it being "Okay to make mistakes".
Later, i texted him, saying i was dissapointed, and Ram deserved an apology.
And guess what Straddy's apology sounded like.
It was something in the means of
"I'm sorry for being brutally honest and stupid, that's just who I am".
I left that without a word of reply.

It all would be somehow forgivabble, if Straddy was even any good. He isin't.
And he always loathes on himself and his skills, only to completely turn around when his ego feels in danger.
And it feels in danger 90% of the time.