The XB1 never recovered from its disastrous reveal event, their messaging that entire pre-launch cycle was a constant stream of fails. Anytime Mattrick or someone else at Xbox opened their mouths they made the situation worse. Then at E3, Sony give them a killshot that ensured the XB1 would be stillborn. It was a more expensive system that was outperformed by the PS4 on day one, saddled with an unwanted mandatory peripheral in Kinect 2.0, and starved for quality exclusive content. Over time, Xbox did work to get rid of the Kinect requirements, lower costs, and try to make the system more competitive, but by that point it was far too late. PS4 didn't just beat the XB1, it curbstomped it over and over and over again. Sony was still turning out huge system selling exclusives during that time, while every time Xbox tried to do something it seemed like a drunk uncle that couldn't hold down a job. Remember the horrific state that Halo: The Master Chief Collection launched in and how long it took to right that ship?
The XB1 could not do what the PS3 did. PS3, too, had a disastrous reveal and lead-up, making things worse on a near daily basis, and was nearly crushed into oblivion by the 360. But Sony not only recovered from the PS3, but made it a must-have console by the end of the generation, eventually (barely) outselling the 360. The XB1 never came close to doing that. It was always doomed to a distant third place, and there was no path to recovery. The mistakes of its reveal and launch damaged the Xbox branding to a point where they tried to reinvent themselves with Gamepass, which has slowly caused the brand to wither on the vine to where it is today and when it's becoming increasingly clear it's not a question of if Xbox will go third party, but when.
Xbox made mistakes in the 360 generation by rushing that box to market, creating the console with the highest failure rate in history and necessitating the billion dollar bailout for Xbox gamers, and how it all but abandoned it's own core audience post-2010 to focus nigh exclusively on Kinect. But the reveal of the XB1 was a self-inflicted wound the brand never fully recovered from and never will. This was the watershed moment where Xbox became doomed to a slow decline, where it now looks over its squandered chances and laments that it could've been a contender, instead of a bum.