I don't think WeWork is anything special, but your argument is obvious and has been addressed: WeWork packages each lease in a separate legal entity so they're not that exposed to swings in individual markets. They also argue (maybe correctly) that in a recession they'd actually do better because companies would become wary of taking on long-term liabilities and prefer the flexibility of short-term leases.

Banks borrow short and lend long. It works out OK for them.

Banks have leverage. We Work does not: We Work can't rent out the same chair to 20 people at once.

Maybe not 20, but I expect that the WeWork hot desk membership does this to an extent. Remote workers don’t usually show up every day.