Don't buy it then.
Fair enough.
Yep - it's not. Anyone interested in a PS3 already has one and there's no reason to trade it in. If you don't have a PS3 then you likely don't have PS3 games. If you don't have PS3 games then you can stream them to your PS4 or even PSVita via Gaikai... so where's the problem?
Which the game you're interested in, Kingdom Hearts 3, doesn't have.
So you were never truly interested in Kingdom Hearts games which are mostly released on Sony's systems since PS2 days.
I said I was partial to nintendo. Not that they were my only systems. I actually have a ps1, ps2, ps3. But I always had a smaller amount of games for them compared to my nintendo systems. Since KH3 is the only PS4 game I want, it would be waste of money.