Does your game allow PvP combat actions? If not, loot sharing should be mandatory because it is, inherently, a PvP action. The normal method of resolving such a conflict would be to beat the shit out of the offender until they come around, but if that's not allowed, what in-game resolution is there? As such, an out-of-game resolution is needed, and that is compulsory loot division.

As with everything - discuss your game before you start playing it so that everyone is comfortable with the style of game you're playing. Acrimony stems from people believing they're playing different styles of game.

If you want to play a character who steals from the group or otherwise acts to the detriment of the group as part of their characterization - then make sure the other players are going to be happy with, and enjoy the style of game you're bringing to the table.

If you're designing a character who steals from the group or keeps loot for themselves, you have to ask yourself... are you making the kind of character that the other characters would want to travel with? If your character is just an asshole all the time, why would they not just... part ways with your character? In real life, would you hang out with someone who kept stealing your wallet or refusing to pay their share of the bills in restaurants or pubs? "I'm just roleplaying my character" yeah, well they're roleplaying their characters too... They're not all putzes, and if spott a raw deal you gotta be prepared for them to ditch your parasitic ass.

If you're relying on them keeping you around simply because it's a game and "it's not fair to exclude your character and it wouldn't be fun if they did that", then you have to be willing to make concessions too (like being open to a full loot share), because it's also not fun to have another character constantly taking all the good stuff for themselves.

Ask yourself if your fun is at the detriment of everyone else's fun. If you're making the game less fun for everyone else on the regular... are they going to want you in the game at all?

DnD adventuring parties are, at their core, a group of people who get along, working together, for their common benefit. If you are designing a character who "doesn't play well with others" it's important to understand that your character's personality is pretty antithetical to the game's core expectations.

Definitely, if you're considering contentious characters like this, also consider making a character with the capacity for personal growth. Maybe you start out solitary and paranoid, or greedy and secretive... but you grow to trust and work with these other people in time. Maybe they learn to be less selfish and make sacrifices for the group. Once these people have saved your life a bunch of times, maybe they realize things are more important than money. Character growth makes for a good story, after all, and that moment where your character makes that leap can make for a great story moment.. just... don't hold onto that growth for too long, because the character might be annoying before that realization.

People aren't rigid in their personalities. Yes, a lot of RPGs make you write down some traits on your character sheet, but if you view them as hard and fast rules that never change for an entire campaign, your characters will feel one-dimensional and shallow.

If the players won't share, I'll tell them what each of them gets

My current rogue started out sharing loot fairly but it's become a running joke that she stashes so much she jingles when she walks. To be fair, half of the party actively don't want money and she'll share when asked (if she can't get the five-finger discount on whatever the party's trying to acquire) so essentially she's acting as the party bank.

Session zero is your friend.

Personally I am of the opinion that some party rivalry is good. You stole that on your own? It's yours, sure. It's not real stuff after all. Who cares?!

But if you are obviously just taking shit in full view of everyone, in a hostile location, with no intention to share...well now that's a dick move and won't be tolerated. Still a good RPing opportunity. I have actually told people before: "my character needs to learn this lesson so please teach it to them", before doing stuff like this. With the understanding in place, it's a cool RP opportunity.

All our loot goes in the party bag so we can distribute it later, then I forget to distribute it and we pay for everything out of the party loot.

It kinda limits the spectrum of playable characters though right? The others can notice that that's going on and either go PvP or kick the person out of the party. It can actually be a cool character arc to teach the character to share loot.

Of the player themselves aren't able to learn that though... do the same as above but irl?

I play an arcane trickster rogue who sometimes goes off on her own little heists to make some money and she doesn't always share the rewards of that.

Also if she really put her butt in danger to get to a secret chest she might take a lil finder fee before anyone has a chance to look.

Sharing loot is ideal and generally I do so but I think it can be fun flavor to be a little greedy. I'm also super ready to be caught ic and deal with the ic consequences of her actions.

Also she's very loose with her money and buys a lot of gifts and carousing so it sorta evens out

Save that for vampire the masquerade!