Steam's most important advertising is actually quite in your face, and used to occupy a good part of the gaming sphere for a couple of weeks each year: their sales with discounts between 50-90% (calculated from the current "regular price" which for older games is often already far below original retail price). They've switched it up in recent years, making the summer sales tamer in exchange for more weekly sales, but the concept stays the same: sell "old" games for prices you can't refuse. And that's why people don't mind: when they tell you it's a great offer it genuinely is.

Everyone else in gaming is fighting for the newest releases. That's the battleground XBox and Playstation use, and that's where newcomers like the Epic Game Store try to beat Steam. Steam meanwhile is pretty toned down on new releases, and is going for long tail sales instead.