Sure, if you are the kind of person to sell and buy used games, that will probably be pretty cheap. But that's becoming more niche by the day, even without Stadia. Most game sales are digital downloads from a storefront.
I have an experienced software engineer's salary, few expenses, and yet... the cost of a whole console to simply play a couple of exclusives (when the vast majority of games are available cross platform and you already own another console or pc) is still too high, even though it doesn't hurt much financially, overall. It isn't an impulse purchase. And it makes you feel like a mark/sucker if you go for it - ~$400 for a video game or two or three is a rip off. And these days, they all have a subscription service you need to buy if you want multiplayer or game updates.
At the same time, I never feel compelled to penny pinch by selling/buying used games. And I like to keep them, as I'm sure many other people do. Time, effort and inconvenience is involved with used buying and selling, and for many of us, that offsets the value of actual dollar savings.
