Are you close enough with your parents to try and have a discussion? Ask about their concerns, maybe work out an agreement like only gaming at weekends, X hours per day, etc? I'm not asking for answers, just teasing out ideas for you. It's very hard to know if you have a problem or not, as it is with just about anything you can become addicted to. The fact you're questioning and not on the defensive is surely a good sign, though. 
I'll start trying in a bit. There's some wind that needs to blow over. Also, some questions need answering. And they're my questions. And time has the answers.
So, yeah. A bit translates into maybe a month, but, I'll get through it. I mean, it's not a bloody all out war below my window, there IS NO OTHER WAY but getting through. Literally.
If the console is yours, as in you bought it so you own it, I think you absolutely have a right to take it back.
"Mom, I respect that you're concerned, but I own my console, and I can't condone you handling my possessions without my permission. Please don't unplug it again."
Respectful, but firm. You're 20 now, yes you have to live there, but they also have to realize that you're not a little boy anymore.
No. I need to be sure myself first. Also, the thing is, my PC is not completely bought with my money. Sometimes, I just couldn't handle the prices. Damn 770's aren't cheap... But they're certainly good at giving you a lot of bang for your buck.
Concern is fine. I need to figure out if it's true, or just a concern.