On the other hand, in a bad economy, more people are likely to rent their extra rooms at lower costs, and whether vacationing or even living for short term, consumers are more likely to pay.

There is then the argument that such a time would quickly be bad for aurbnb bc the fees quickly cost more than the marketing or insurance are worth.

Counter-intuitively, demand for travel tends to go up in rough times.

Do you have any sources on that? I have family in the hotel industry and anecdotally the entire industry in my area took a nose dive in the last recession. Not quite the same as general demand for travel but it's more relevant to how Airbnb would perform in a recession.