They were never really in it. The problem with Stadia is the lack of compelling 1st party software. Instead of investing in games early on, they released a service and then invested in 1st party studios which means it will be at least 3-4 years before one of their games releases, which leaves Stadia to survive solely on 3rd party titles. Amazon did a slightly better job at this, but still is missing any kind of compelling software to get gamers invested in the ecosystem.

Microsoft was not new to gaming when they made Xbox at all. They had more than a decade of experience in it. They had the MSX gaming system in Japan in the 80s. You know the system that gave birth to the Metal Gear series. They had years in the PC gaming space with games and controllers and joysticks. They partnered with SEGA on Dreamcast. Which used WinCE and Direct X 6. Every console company that had some success since the 80s had some background in gaming. From Arcades. PC Gaming. Publishing games and/or making chips and hardware for Nintendo/SEGA.

SEGA was in Arcades first.

Nintendo Arcades.

Sony. Publishing games on SEGA systems and made the sound chip for SNES plus the Nintendo PlayStation CD add on.

MS. MSX. PC Games plus controllers and working with SEGA.

Google? No background. That's why they thought it was a good idea to hire Phil Harrison. Who helped with the disastrous launch of PS3, Xbox One, and Stadia.

Amazon? No background. Why they failed twice already. Have people running the gaming division who never played a game and know nothing about them and don't let women have a voice.

Apple?. There was the Pippin which was a disaster. So there is that...I guess.

and not only the expertise. I will be worried when a big entertainment company like Disney goes and make their console. 

That was after they left consoles. I was talking about a companies history in the industry before they had some success in consoles.

I still think Stadia was always about Google finding a way to repackage old unsold Chromecasts that they couldn't figure any other way to get rid of.

So what happens now?

A slow decline, then bam, sorry folks no refunds for your now defunct purchased games.

If MS hadn't come along with xCloud (a much better offering) they may have been able to keep Stadia trudging along a bit longer. But, the value proposition sucks, their marketing of it was/is severely lacking, and, as such, it never had any shot. Even without xCloud to compete with, Stadia wouldn't have worked unless they put some serious marketing money behind it. The fact that they didn't do so tells me that Google didn't have faith in the service.

Saying "the problem with Stadia" when talking about it makes it sound like it only had one problem, which is being mighty generous.