I think you're missing the point. There is no such thing as nirvana. Here's haven, here's hell, and it's far from ideal. In an ideal world, we wouldn't need bitcoin --or money in general. We wouldn't need food to survive, 8 hours of sleep, there wouldn't be diseases, wars, and unhappiness.

For the same reason, you can't just make the arrogant assumption that your machine will be free from malware if it remains Internet connected. You don't have 100% security, nowhere. Neither permanently airgapped devices are 100% secure. It's just one factor less to account for.

Of course and it's possible. It's possible to have a hot wallet which never gets compromised. It's possible to download bunch of non-reviewed software in the same machine, such as cracked programs, and still not lose a penny. In fact, it's even possible to guess a private key with a million dollars worth of bitcoin. What's possible is not relevant. What's relevant is what's probable, and it's a lot less probable to have your wallet compromised if it lives in an airgapped device.