To be fair, it's not like there is much else to buy on the PS4. KZ selling over a million units isn't surprising. As I recall, 3 did pretty good as well and KZ had some hype behind it. It's the only PS4 game I've bought so far myself.
To be fair, there isn't much to buy on the Wii U either.
I was just simply addressing his point of poor sales. PS4 games are doing pretty well considering the installed base.
Side note: NFS Rivals is amazing if you like racing.