Well, physical media breaks, discs get scratched and you might no longer find the updates.

If you want to preserve your games nowadays your best option is buying from GOG and backing up your installers (it’s DRM free and with no launcher). But it’s a massive hassle compared to just using Steam and having auto updates. The GOG launcher that does updates for you exists, but it’s a bit meh.

Anything that’s delisted will, outside of piracy, die when the account holders die.

Not totally true, it’s allowed to bequeath your account to someone through your will. At least for your Steam account. Of course you have to take care to do that before you die…

Valve isn’t going broke anytime soon, they get around a 30% cut of every game sold and on top of that they also get a cut from all the steam market transactions. Valve is a privately owned company, which means no shareholders who want constant growth for any price, so for a company worth around 7.7 billion USD in 2022 I’m really not afraid Steam will go away anytime soon.

And even if Steam has to shut down, Gaben at least made the promise to give you downloads for all your purchased games. You can decide how much that’s worth.