Pretty simple really.. 

My PC already does everything I could ever want from an XBox.

This is the first generation I don't have an Xbox console. Though to be honest, my 360 got about 1% of gaming time last gen.

This gen, I have a PS4 and a gaming PC. For the tiny handful of games I can't currently play, very few of them interest me anyways.

Not really interested in most of their exclusive games.

I got a 360 for their Halo games...but then that was all it offered me so I wont be doing that again unless they get more exclusives that appeal to me.

DRM and some launch games not being complete on disc

basically fucked up launch

Exclusives are a big thing for me and the Xbox exclusives rarely catch my eye. That said,the X360 was a great console but I don't have much of a reason for Xone. What the console provides I can get on Sony,Nintendo and PC and the lack of exclusives compared to these three gives me the impression that the console provides less than what I already have,so it buries my interest.

I'm not interested in the vast majority of games on the XBox consoles. XBox has mostly Western games, and there are very few Western games that I like.

I don't own an xbox one yet but Im interested in sea of thIeves and pubg. There's no game I'm interested for switch this year so I might trade it with odyssey and xenoblade 2 for the xbox one x.

Many reasons.

360 was pretty bad compared to Xbox imo.

Competition is looking stronger.

Too expensive at launch, and now it seems too expensive for the true console (XB1X)

Most games on PC or PS4.

SImple for me. Exclusives.