Well, you can get more for your money.
So if you want a PS4-equivalent PC, you won't pay quite as much (especially considering that PSN and XBox Online are $50/year) -- you just won't be able to play console-exclusive games. Of course, there are also PC-exclusive games, so really you need to pick what you want to play. Elite: Dangerous might tempt me into a PC since No Man's Sky is kind of a bust: it's only available on PC and XBox. But like I said, Uncharted is really, really good and it's PS4-only.
However, now that the consoles are beginning to release hardware updates, one of the PC's advantages is lessening, but a new upgraded console might be more expensive than an upgraded video card as long as you're not buying top of the line.
If I don't want to buy a whole PC, an external drive for my MBP might work. It's not really a gaming machine though, especially since it's going on 3 years old.
However, now that the consoles are beginning to release hardware updates, one of the PC's advantages is lessening, but a new upgraded console might be more expensive than an upgraded video card as long as you're not buying top of the line.
If I don't want to buy a whole PC, an external drive for my MBP might work. It's not really a gaming machine though, especially since it's going on 3 years old.