What are the virtues of getting a 1080 Ti Desktop over buying a PS4 ?

I think this one is simple at least as a choice.

All games built for the console are optimised for that console, which makes it seem like it's punching well above its (computing) weight. If you run the same game on a budget PC. because the games are usually designed for a higher spec machine you often have to cut back on draw distance, number of objects on screen, etc.

For the casual gamer like myself a PS4 (or X-Box) is a much better option, i can chill out in my armchair in front of the T.V. relaxing playing games, it also makes a great streaming media player and, blue ray player. I have a very decent specced P.C. but the only graphics intensive program I now play on it is Second Life.