I'm not...
Assuming that all of the "basics" (HDD, SSD, good monitor, case, little stuff like optical drives / wireless cards etc.) are already in place, to stay up to date with PC gaming (play the latest releases on "high" or "ultra"... not even top of the range), like I said you need a new CPU (and therefore almost certainly Motherboard) every 4 years and a new graphics card every 2 years.
Assuming, then, £250 a pop (a decent estimate for a good graphics card or mobo/CPU combo at any given time) you'll have 4 graphics cards and 2 CPU/mobo spends in 8 years... so £1500. And that's assuming that you don't want to upgrade anything else, like gaming KB / mouse or a new monitor. And actually thinking about it... you're likely to need at least one HD / SSD replacement in that amount of time.
You CAN push it for longer between upgrades but you'll be playing new releases on "medium" settings and probably at a reduced framerate - usually still better than a multiplatform counterpart on console but... annoying, especially if you go looking at videos of the same game on full settings.
I've definitely spent at least £2000 on PC hardware in the last 8 years, and I only do the bare minimum as I've got mouths to feed and can't justify many big spends. That only works out at £250 a year so it's not huge... BUT, if I was young, free and single I can guarantee I'd be spending more. I only bought my current graphics card 14 months ago and I'm already itching for an upgrade
.
In contrast, in the same amount of time I've spent less than £500 on console hardware... a PS3 quite close to release, a 360 late in the game for £90, and a few controllers etc.
On the other hand, while I've probably spent over £1000 on console games, I can't have spent more than a few hundred on PC games.
So like I said it's hard to work out what's more costly... although, obviously PC has the clear "bang for your buck" advantage every "cycle" as it overtakes the latest console generation within a couple of years. For example, the last game I played through was The Last of Us on PS3 - probably one of the best games I've ever played - but there were SEVERAL times when I found myself thinking "...this would look so much better on PC".