Despite the terrible launch of XONE (Onlne DRM, which was never implemented, Force Kinect, which no one asked for, etc.), it got good sales, a good starting lineup of games, and had partnerships with such mastodons as COD.Thats icon era narrative, not the whole story. The damage was done before the Xbox one launched. There was inertia but also lots of 360 to PS4 switches.
MS dropped the ball from 2010 onward and lost a lot of momentum. Sony knows you can start slow but it's more important how you end a generation to gain goodwill toward the next. And uncharted 2 onward they showed that.
There were lots of folks that switched from 360 to PS4 due to this. Even without taking the PR launch shit show into consideration. Hell I would even go back to RROD as a cause. If I had a console that had to repair one or more times, sure as hell I would switch brands.
The situation was not as bad as it is now commonly believed, it could be fixed. But then came Spencer, who arranged ports to PC and the launch of GamePass, and this finally crushed the chance for the future of XONE.