One reason I like Sark as a villain is that he's slowly realising that he's in way above is head, that he's just a pawn in a battle between divine forces beyond his comprehension. On the one hand, he's basically sold his soul to the devil, in the form of the near-divine Master Control Program, an entity that wants rule not only the "mortal" digital world, but the world of the "gods" (Users) as well. And opposing him, there is the warrior chosen by the gods (Tron) and one of the gods themselves (Flynn). There are many scenes in the film where Sark expresses more or less subtle fear and doubt, sometimes trying to disguise it with anger (my favorite instance being when he almost hisses at Flynn "you are NOTHING!"), all of course brilliantly acted by David Warner, and beautifully accentuated by his circuitry glowing brighter in his rage.
I recently read a post about how Sark and Tron barely interact at all before their final fight, and that this would make that confronation less emotional than it should be. But I think that at least for Sark, it's a very frightening situation, having to confront the divine champion carrying the weapon blessed by the gods, and being unable to run away for fear of the wrath of the MCP. Even if he doesn't know Tron personally, he knows what Tron represents.
This is also somewhat reflected in his "real world" counterpart Dillinger, who is also slowly realising that he's not as in control as he thinks he is, being blackmailed by the computer program he created.
Where’s the “you have no memory if you loose your disk” come from?
I’m assuming it is in uprising and the fandom just ran with it because in the movies it’s blatantly false.
Greetings. The Master Control Program has chosen you to serve your system on the Game Grid. Those of you who continue to profess a belief in the Users will receive the standard substandard training which will result in your eventual elimination. Those of you who renounce this superstitious and hysterical belief will be eligible to join the warrior elite of the MCP. You will each receive an identity disc.
Everything you do or learn will be imprinted on this disc. If you lose your disc, or fail to follow commands, you will be subject to immediate de-resolution. That will be all.
Once again how Flynn was there for the speech “huh they’re giving this thing to a very specific few and no one seems happy about it” and then went “I liked the frisbees I’m going to put them in my world :)” is so wild to me. I know it was probably actually Disney higher ups who just…. Didn’t think about the implications of making it mandatory for all.
Classic-
In the classic grid it was assigned spesifically by the MCP to the video warriors, gladiators, combatants etc (whatever you want to call them).  Essentially it makes  eradication easier. If you were in the game grid you were one of three things:
1.) Religious
2.) rebellious/just want to do your function
3.) “useless”
Keep in mind the MCP was different from Clu, he wasn’t reprogramming he was assimilating. Took control of all your functions, made it so you wouldn’t want to complete them or talk to your user. You are apart of him now. Apart of one. If he found you useful. If not your in the games to eventually die there. The disks just make it easier to pick up what useful information a program may have while  simultaneously getting rid of the body.
You don’t loose your memory when you loose the disk. It’s a memory backup! Basically it’s a hardwired flash drive in your back!! If you loose it they just kill you (this is to prevent rebellious programs from destroying theirs or refusing it).
Legacy-
Ok well then is it different In the other grid? Slightly. Flynn didn’t intend it as a oppressive tool but it canonically serves similar functions later on, we here the later part of Sarks speech as a safety speel in the armory before Sam is sent to the games. “Take it off and well fucking kill you”. This is under clu. Under Flynn I’m imagining it was mainly memory back up and so he could have quick access to code/be able to code from inside.
If you still want to use the memory loss trope that’s fine. I’m just, really curious where it started because it’s not exactly the case?