A dedicated Gaming Computer needs "lots of grunt" and it is the graphics card, mainly. They can be rather expensive. I seldom attempt to play games that need the "grunt" I have but ....
I actually leave my "gaming" computer on almost 24/7, reboot it every so often. I do turn the laptop off every evening though. Never opened either to check the fan.
Buying a VERY cheap computer "off the shelf" can be a problem ... but if all you do with it is search the Net and Forums, most people wouldn't even bother to "upgrade" it, unless something went "toes up".
You are not just paying those "local computer guys" for the upgrade of RAM but the $60/hour for the person to open your computer, remove the RAM, fuss about, have a coffee, and install the upgrade.
Depending on what you have you could probably upgrade to, maybe, 8 GB ... I can't see you needing more than that. You should be able to do that yourself ... it is no big deal. Dr Google is your friend.