First off, I absolutely loathed Subnautica, gave up on Assassin’s Creed Origins after about fifteen minutes after dying constantly everywhere, gave up on Stardew Valley after about five minutes due to frustration at the constant grinding time pressure and not being able to refill the stupid watering can, haven’t been interested in first person shooters since Wolfenstein, enjoyed the modern-day parts of Assassin’s Creed IV Black Flag, think board games should have an option to enter your own die rolls, had this kind of experience with Assassin’s Creed Valhalla, and think Jim “Stephanie” Sterling is completely on the money nearly all the time but relies too much on running gags and grossouts (plus deep down I suspect his transgender/nonbinary thing is an act, but I’m not bringing it up on his channel), which by prevailing standards makes me a goddam alien, so if you don’t respect my opinions, I understand.
That said, I like helping people with simple stuff, and I don’t usually quibble about intentions, so here goes nothing! 
Gamestop: I remember those heady days of the PSX, Dreamcast, and PS2, where I’d rummage through shelves for half and hour or more and walk out of there with that one hot game I had my eyes on or a fistful of clearance titles. No downloads back then. When the seventh generation (PS3/XBox 360/Wii) rolled around, being able to pick up used game for a great price and not having to pay full price online was a major boon. This was also the time Blockbuster Video and its game rentals were heading to the dustbin of history, making Gamestop even more important for players on a budget. In recent times preservation has become a big issue, and there’s been a real push to preserve physical media. Bottom line, having real, solid hardware in your hand is a big deal for a number of reasons. I’m not surprised at all Gamestop has survived this long.
Inadvertent purchases: It’s happened to me a few times, but usually due to not reading carefully rather than clicking the wrong button. The real (and very massive) problem is predatory practices like lootboxes, microtransactions, and season passes, which Jim Sterling has covered in depth. There’s also bullcrap like the purchasable quantities of consumables never matching the amount needed for a specific benefit so you always get too much or too little…
Dirtbag companies: Not all of them, but far more than there ever should have been (again, Jim Sterling’s covered this numerous times). Keep an eye out for unethical practices (crunch, mass layoffs, sexual harrassment, abuse, etc.), and never take a AAA executive at his or her word.
E-sports: Why the UFL? Why cornhole? Why chase tag? If enough people make it a thing, it’s a thing. Don’t tell me something as ridiculous as baseball became a “national pastime” for any reason other than a whole bunch of men wanted it to be.
Steam: Other members have already answered this better, but for me, it’s a great place to just look around and say “Wow, this really exists!”…and then get it, just like that. Haven’t had that kid-in-a-candy-store vibe since the early days of Blockbuster Video. And yes, that indie developers can go there and get the fruits of their labors without some parasitic AAA greedbag taking all the money and credit absolutely rocks.
Subscriptions: If you mean season passes, I don’t buy 'em; total ripoff. If you mean periodic payments required to play certain mobile device games…I don’t buy them, absolutely atrocious idea.
Art form: I consider certain elements, like background design and music design, artistic, but calling a game itself “art” is a bit iffy for me. If calling it art means that there’ll be more of an effort to preserve these games, though, I’m all for it.
What should everyone know about: Two words…Touhou Project. I cannot overstate how massive this has become. There’s a good chance that if you have any exposure whatsoever to doujin games, the eighth generation (PS4/XBox One/WiiU), Steam, or mobile device games, you will play a Touhou game, either the official games or any of a myriad of indie projects, spinoffs, and licenses. I mentioned LostWord before, didn’t I? 