I don't think your problem is your 12 yo wanting a console, OP. It's that your 6 yo will likely end up glued to it as well (not to mention your 9 yo). You might need to think now about how you are going to manage that (though you'll probably have lost the will to think about it by the time it comes to DC3).
My DS (my oldest child) saved up for an X Box for absolutely ages, and finally bought it when he was 12.5. It was a flipping nightmare - endless arguments about time spent (we had rules about this, obviously), attempts by him to hack into our broadband when I switched it off, etc, etc, etc. I confiscated the power cable, and he saved up his allowance to buy another one. I heartily wished I could dump the blasted thing in the sea. It caused endless problems. The 'age ratings' were also a problem. I said no to anything with an 18 rating - but that rules out pretty much everything on XBox. So we gradually compromised on 15/16 ratings - but then 'everyone else' has Call of Duty, and so you somehow end up with that, too.
That said... he's now 17 and says gaming is 'a waste of time when there's so much more interesting stuff to do'. He sold his XBox on Ebay a couple of years ago (he was going to chuck it, but I said he might get something for it - and he did. Not much, but enough to be worth the faff of advertising it). He goes running, reads books (he's always been a keen reader, but was less so when the XBox reigned), watches people blethering crap on YouTube, talks endlessly to me, reads the newspaper, winds his siblings up, meets friends, etc.
So it isn't all gloom and doom, even if you have a pretty torrid time meanwhile. He is my obsessive one (hence his complete rejection of it now). My others are girls, and have never been bothered by gaming. Social media, OTOH...