I once worked in a central London pub that wasn't doing very well - however they had the lease on all 5 floors, including the landlord's apartment at the top.

They opened one of the staff rooms on the second floor as a hostel dorm with a couple of beds, filled them no problem. By the time I left the entire building, apart from the bar itself on the ground floor, was hostel beds. £20-£30/ppn, 90 beds, nearly always 100% occupancy - a license to print money!

Sadly Covid19 will have crushed them I suspect.