By the way, have you seen the anime called "Ruin Explorers"?
Yes, many aeons ago my picture was Ihrie!

I should probably get a new picture of some kind.
EDITED IN - Sadly the only breakdowns left online (how few there are!) seem to feature "Loonie" rather than Power Gamer, but I remember long, long discussions on what was a Power Gamer (which we now call an "optimizer") what was a Munchkin (which I think we would now call a "jerk", particularly "that jerk who intentionally breaks the game") and so on.
For me the difference was never more perfectly exemplified than in a CP2020 game, where I had a Power Gamer and a Munchkin.
The Power Gamer's PC was seriously tooled-up, had his stats in the right places, was great at his job, and a horrible menace in combat, but he didn't wildly invalidate other PCs, nor bend/twist any rules to get there.
The Munchkin's PC was... a walking rules exploit. Not just "good math" or "highly optimized", but bending the rules as far as they would go for the sole purpose of ensuring he could kill absolutely anyone who wasn't in power armour or a tank (being in an armoured car was insufficient protection!), and he did so in a very implausible way that only worked because of the peculiar way the game rules were set up.
(This was another time that setting expectations didn't do enough! We'd strictly limited availability on some stuff, discussed how high stats would go, how low humanity or whatever it was called would go, what money could be used, and that everyone needed skills beyond combat, but this guy slid right through the middle of that! He didn't need to go to extremes, because the game had just made it too easy to do what he did, all with seemingly individually harmless or even good rules, unless you combined them!)
(On top of this personality issues factored in - the Power Gamer, like virtually all optimizers I've seen, was a team player, eager to work with others and do his job well.
Whereas the Munchkin wanted to make the game about him, and his spectacular, head-shot-filled victories, even though they didn't really improve the game or make anything more meaningful for anyone. He was quite happy to sabotage a scene (though I don't think he did it consciously, and it was in-character, such as his character had a personality) and turn it into a firefight at the drop of a hat. God help you if you planned on doing a stealth run! He'd agree to it, but the moment any potentially enemy being with a head got into range, that head would explode, and as silencers and flash-hiders reduced the performance of his guns, they were right out...

)
Actually that's interesting to think about - it's more or less exactly the same thing as people who insist on playing useless characters, just with the reverse. The "I must be this useless guy who cannot play well in a team!" player essentially also wants the game to be about him, he's just not focused on victory, or if he is, it's in an arena other than combat)