Many did, but:

1. The retirement of Google Reader sort of signaled the death knell for RSS. No, every RSS feed didn't shut down immediately. Yes, there are still zillions of RSS feeds live today in 2023. But it was a sign that any RSS feed you cared about wasn't likely to be around forever.

2. Many did switch, but Google Reader had some basic (but nice) social features. I think about 99% of my friends never made the switch to something else. So I miss seeing what my friends starred.

At the time Google Reader announced it's shutdown, alternatives didn't really exist -- the idea of creating an alternative and competing against a free product from Google didn't seem too economically feasible.

There were other RSS clients, but Google Reader's web-based, infinitely-scrolling interface was unique. Imagine any utility software you use daily, now imagine it being gone and having to use some alternative you know is inferior.

Fortunately a number of alternatives were quickly developed with different levels of success. But few were available the day the shutdown was announced.

I switched to different readers since then, but I'm still disappointed because 1. GR was in many ways just better and simpler (before they starting shoving sharing down the users throats), and 2. kind of sad the whole RSS feed subscription thing remained niche, seems like after that most large social networks/blogs started dragging users into their proprietary feeds, and then a lot if that got crushed by ads and dumbass "suggested for you" content which by now got so annoying I don't even want to use most services anymore. We've gone a long way from simple RSS/readers and not in a good direction : (

People could and many did.

However Reader was a useful, beloved, and rather… intimate product, it was one which closely held your interest and part of your daily workflow.

For its users, its closure sent a clear message: Google has stopped caring, it doesn’t matter how important something is to you, or to an ecosystem.

Personally, it’s the moment I stopped being comfortable using google products for anything essential.

I remember trying the alternatives back then (feedly, newsblur, etc) and they were just not as smooth, possibly because they were struggling to cope with the influx of Google Reader refugees.

People who cared enough did just that. I also don't think the main problem was Google Reader going away but the signal that it sent ("RSS is going away").

To be fair, the sites I care about all still have RSS support though.

That's because the goal of the whining is the whining - people feel emotionally slighted because someone didn't keep maintaining a free product just for them. This explains why paid alternatives didn't take off - people wanted FREE and they wanted GOOGLE to GIVE them FREE. It's modern developer entitlement at its best - it comes from the same place as all of the abusive attacks on opensource developers when they don't cater to the audience.

Google reader was also an archive of all the RSS feeds you had subscribed to, or someone had subscribed to before you. So you could get things that were no long let online

The damn google reader had a unique ecosystem of users resharing/starring interesting items.

That's exactly what I did. I also switched to a new browser, email provider, and search engine. Haven't looked back since :)