Alright then. I disagree that it’s fair business. I don’t think it even qualifies as business; I’m not paying for a Trading Card service here.
You used CS:GO items as an example for this case, when that isn’t actually how Trading Cards work. Not even touching crates, keys and so on. Trading Cards work by offering you half of the potential drops required to make a set for one game (rounding down, if it’s an odd number). That’s it.
Your only hope from then on is accumulating pennies from Steam Sale cards / inventory items (literal pennies) or the very infrequent booster packs to try and round out a single set, a level of which on a badge grants you 100XP towards your profile.
You can get additional bonuses during sales from spending in the Store, to the tune of a bonus card (or booster pack?) per $10 spent.
I don’t really call that fair business, personally. I get no benefit out of Trading Cards. They sell for literally pennies, the cut Valve gets from each sale often exceeds what I make on it (£0.05 is what most event cards go for, the cut is what, 2 or 3p?).
Now, crated items in games in CS:GO and TF2 are a different story, but are also reliant on investing money in keys to unlock randomised items (a la the lootbox controversy that games like Overwatch are being investigated for) that might be rare enough to be worth selling. DotA 2 as well, forgot about that one.
And this is just one part of Steam that drives money Valve’s way. The only advantage to the consumer of regular Trading Cards (as Foil cards are very, very rare drops, and Booster Packs don’t drop that often either in my experience, speaking as someone who maxed out the Borderlands drops years ago and have probably less than 5 Booster Packs across BL2 and TPS for my time in them both) is XP for your Profile, and the occasional badge level for one game.
Am I being unfair? Am I being too harsh?
I worry I’m getting way off-topic, which is also why I didn’t want to get too far into this.