It's not scalping. The keysellers are what fuck over regular consumers. Steam sales used to be known for their crazy discounts, but as soon as keysellers began buying thousands of keys at those sale prices and then reselling them for a profit that pretty much died and now it often takes years for well selling games to get a decent discount.

This has nothing to do with Steam being the only legal store front. It doesn't matter how many legitimate store fronts there are, if key resellers scum profit for themselves out of a game ever having a sale on any of them then those sales stop happening.

Of course if you buy a product you should own it, but if you buy it from some guy in an alley wearing a trench coat for 20% of the actual price then you don't get to be surprised when the thing doesn't work. It doesn't matter if it's software or hardware, when you see something being sold for a fraction of the price the actual creator sells it for at a place that isn't an official store front there's a reason for that and that reason might be that it's stolen and effectively worthless. If you don't buy from the creator or an official seller of their product then you don't have the right to complain to them. It's not Nintendo's fault you bought a stolen Switch 2 of of a social media ad and they bricked it because it was reported stolen by the actual owner.