I mean… I guess I could also ask that. (Though, being a very big Sonic fan, I already know what went wrong for the most part: console gaming was still new, and Sega didn’t fully understand the importance in committing to generations for longer than a couple of years. Plus, Sonic Team & Sega experience an awful schism between US and JP.)

But right now I’m focused on Xbox. These are my genuine thoughts, and how I felt as a casual consumer during 2017/2018.

Console gaming was not new when Sega released their first console the SG-1000 on July 15, 1983 since the Atari 2600 launched over five years before it in September 1977.  Heck even when the Atari 2600 launched console gaming was not that new since the Magnavox Odyssey launched in September 1972.

The industry was still in its early years during the 1990s, this really isn’t something you can dispute. Yes ofc there have been consoles dating all the way back to the 1970s (the Vetrix was the original IIRC), but e.g. the idea of Nintendo creating a successor system to the SNES—releasing games exclusives to this system—was a novel concept back then.

No, it was not console gaming was popular in the US which is the biggest gaming marked in the world since the early 80s with the Atari 2600.   Again, the early years of console gaming where already over by the time the Sega S-1000 was released by that time there where already dozens of other consoles released before it.

Well, it appears we have a different perception on whether the label “early years” is adequate to describe the 1990s for video game consoles. Not much to argue, this is merely a matter of opinion. So, I’ll drop it.

Early years is the first five to ten years of something existing.  So yeah, the 90s was nowhere near the early years for consoles and the Sega S-1000 did not first appear in the early years of console gaming either again dozens of other consoles released before it.

I mean, you could kinda say the same thing about Xbox, that only the 360 was really an unqualified success, and even that was sabotaged by shifting their focus to Kinect and then going all in that sort of thing with the Xbone.

Besides the original X Box they all easily sold more than the Atari 2600 which was the first successful home console so no you can't say the same thing about the Xbox.  Also, people forget that the original XBox easily outsold the Gamecube and more than doubled the sales of the Dreamcast.  So, on their first try you can argue the already accomplished more than Sega did with the Genesis/Mega Drive.

Xbox basically died after the Xbox One. Bad publicity thanks to Satya "Heh heh, AI!!" Nadella has made things worse.

The market was simply far bigger in the 6th-9th gen than in the days of the Atari 2600 or Megadrive though; in the 2nd gen, the winning console of the generation sold 30m, while in the 4th gen the winner sold 49m, while at the same time that the OG Xbox sold 24m, the PS2 sold over 155m.

OG Xbox was outsold 6:1 by its primary competitor, Xbox One was outsold around 2:1, and the Series is on track to be outsold by like 4:1. Only 360 was actually competitive, and even then it finished in 3rd place behind Wii and PS3.