I mostly grew up with console games, and I was a console gamer for too long before I switched to PC gaming.
What I liked in console games? Well, they were basically "plug & play", and I was lucky to be able to transport any console to any place in my home or when I was travelling, so everything was easier and I wasn't picky about the graphics. I didn't have a gaming PC (just regular for working PCs :P) and mostly I used mine for point & click adventures games and emulation of older titles.
Why did I changed to PC gaming? The price, inability to tweak my games or upgrade/improve my consoles, and the quality of the later games vs. PC versions. Here at least, the console games are very expensive, and while I was able to get 1 game (or 2 if I was very lucky) per month, and comparing the performance and prices to PC, I started to think that maybe it was about time to make the big jump. Others prefered to pirate the games to compensate the expenses, but that's not the way I roll... (:P)
So I started saving to get the best PC I could in 2011 and by the end of that year I built the PC I have today, now upgraded in RAM, video card and monitor. I get much better performance and much better graphics than in consoles, some games can be modded, I can tweak whatever I want, and can buy at least x10 games than before per month. Bundles and the offers make my life much easier, and so far considering everything, I haven't spent so much and probably less than I would do with the first couple of months with a PS4 or XboxOne. I've been also re-buying my favorite games now on PC, and the differences are astonishing. There's no way I will be back to console gaming. My last purchased game on consoles was and will always be Skyrim for the Xbox 360 in November of 2011.
PC gaming have also relaxed in the later years, now I can plug my Xbox 360 controllers and connect my PC to my HDTV/Monitor and play with a big screen, something that I liked with console games.
Now to answer the main question of this thread: I have two friends that are hardcore console gamers (but less than I was... :P), one of them (Raúl) have an Xbox 360 + PS3, and the other (Alejandro) just a PS3. When I started showing the differences in performance and graphics (especially for the games they know), bonuses and prices, and also games that aren't in console, and they started to like the idea that much that instead of saving for the next consoles, both started to save to get a gaming PC. Both started by creating an Steam account, learnt the new mechanics and bought some games from bundles or during sales that they could play in their current PCs, and when they get used to this new way of playing, they decided that they won't buy a console anymore...
Now Raúl had just built his new gaming PC and during this weekend he will finish to set up his system. Alejandro is too busy re-playing Skyrim now on Steam (he had it on PS3). So far, I think I had turned two souls to the dark side... I mean, to PC gaming successfully ^_^
The only problem for them are the games with no support to gamepads, but Xpadder helps a lot to them.
I say, just show the benefits of PC gaming in the simplest way to any console gamer, and they will get the idea. At least that way they will consider it. Now, about the exclusive games in consoles, just show them the games that they can't play in console, and problem solved... In quantity they are higher, and better anyway (:P)