In the short term, this seems like (and may indeed be) a positive trend - people are able to squeeze into better quality apartments than they otherwise could have. But in the medium term, as we now see in SF, market prices simply rise to account for this "new normal" behavior. Unintended consequences follow. First, someone who is not willing to open their apartment to part-time airbnb'rs is now at a disadvantage. Second, at least part, and perhaps most of, the extra airbnb income is now passed on to the landlords in the form of higher rental prices.
Remember it doesn't matter how much money you have, it only matters how much money you have relative to other people who want the same things you do.