Even within; between funding sources or position switches, you might lose access to your institution's library, or your institution might be small with significant gaps in their subscriptions.

Ultimately, Sci-hub is often an easier and more pleasant way to get papers you have legitimate access to. At this point, I don't think there's anyone in my department that doesn't use Sci-hub from time to time. It's basically expected that anyone on filing fees for dissertation writing will use sci-hub rather than go through the hassle of requesting a special library access code (since they're no longer 'paying/earning' tuition).

There's no going back.

And even within academia. Big universities can afford to subscribe to thousands of journals; small universities and research institutes can't. When I worked at a research institute I would routinely encounter paywalls trying to access papers.