Same case with Master Gu's fiancee, his sister, and many others.

Different timelines. Time irrelevant.

Good question. Nie Li didn't have much comrades or resources to fight against the Sage Emperor in his past life, so its an answer that is revealed slowly and one by one.

That's what the Ancient Beings are counting on Hasting to do, having him to use "balance" as an excuse for them to do things. The Tower's administration cannot do much when there's a plausible cause for events.

Take Hasting's dungeon raid and Rick's partner event for example:
1. Hasting's dungeon raid was treated as a blink of an eye by the Tower administration because the power level balance on the MC's team is too OP, it will serve as a proper awakening call for everyone else outside the tower to level up or perish in the long run.
2. Rick's partner event, although some or most of the profits will go into the MC's pocket as commission, will equalize and redistribute the coins used and spent by and upon the players on the Tower, not to mention a fun event like this promotes people into entering the Tower on top of what happened with Hasting's dungeon raid.

Its not just a song, its a vibe, its a way of life.

You've got your rules and your religion,
all designed to keep you safe.
But when rules start getting broken,
you'll start questioning your faith~

In the rich man's world.

Like I said in a previous comment chapters ago, why would Master Gu resort to stealing when he can just straightout commit DAYLIGHT ROBBERY?

He's not robbing... YET.

Master Gu: Time to flex a little.

Oh, he will. Otherwise it will be unfair to the other two, and it can break apart his decided harem ending as well.

Not yet, we still have the other two weddings to witness.

Not just the author, but also the girl's too.

The easiest reason we tend to choose beach or pool dates often is because there's little to no deception to our eyes of the partner (zero to no makeups, and pretty much exposed body shape). They say eyes are the windows to the soul, but vice versa implies just as well.

TLDR, but this one line from you sums it all.
"That element IS in play, that he does things that seem sane to us in the modern world, but don't seem sane to the murim people."

He's only "crazy" because he's about the only person with a sense in a world full of people who kill others for things like fame, glory, riches and so on (aka the murim).

https://i.postimg.cc/MTJXGVGF/i.jpg

Crazy Demon is literally about a normal person living in a world of crazies, and yet its the crazy people calling him crazy.

A knight acknowledged by the gods of flames, war and savagery. That's pretty much Doom Slayer attributes.

He's just spiteful of the MC. Though I can quite get why he's such an ass to the MC, I mean, EVERYONE wants him, but everything he does to those obsessed in him is a relentless straight-up middle fingers to the lot of them.