@Ineke46 The problem is that from what I have read, travel insurance first requires that the customer exhaust all other avenues of refund before the insurance will pay out. So if Airbnb has an EC policy which covers a positive Covid diagnosis, the travel insurance wouldn't pay out anyway. Airbnb would have to stop refunding guests outside the cancellation policy altogether, which they show no will to do.
Airbnb changes things all the time and doesn't notify hosts. So it's important to check the policies on a regular basis. And that's what participating in this forum is really good for, rather than only coming here if you have an issue. Hosts here are really good about posting "Heads up, fellow hosts" topics, to share some new Airbnb change they just ran up against.
And yes, if you can diversify, it's always good not to have all your eggs in one basket.