Where "most people" is just the few people who actually used it? So basically, most people who like [unpopular thing] think that [reason that thing is unpopular] isn't a problem.

It didn't reach mainstream adoption because most people who care about games didn't think it was a good deal and input lag was a big part of the reason why. And people who don't care about games... didn't care about Stadia for obvious reasons. The target demo for Stadia was basically people who have a mild interest in gaming but not enough of an interest to already own hardware suitable for running games themselves. That was never going to be a profitable niche.

I've always felt the Game Streaming market was lower powered PCs, or something you can get "for the grandkids when they visit". People who have invested in having wired connections to their boxes (try pinging your wifi router sometime) and making sure their LAN and internet are quick probably also have invested in their actual systems. The cost of the games they play isn't the major driving force of their game choice.

You could equally conclude that one of the reasons that very few people used it was because of the input lag.

The major reason stadia failed was sentiment.

Why buy games full price? All my gamer friends say its crap!

Google shuts things down, why invest?

The tech was pretty good for casual gamers, it also pushed linux gaming in the AAA studios.

I think a lot of negative sentiment also came from gamers thinking that Stadia intended to replace their gaming setups.

I will tell you I 100% refused to buy anything from stadia because I was sure Google would cancel it in a year or two. You can attribute sentiment wherever you want, but Google failed because it was Google, not because it was a bad idea.