Some business activity is profitable, some is only break-even at best. If you run a "walk in" operation you have to accept that some business is only marginally profitable. The payback on the less profitable stuff is goodwill plus dilution of overheads across more total revenue. An inner tube is not going to cost more than £2 wholesale, so any price higher than £2 is a profitable sale. I'd happily sell £2 tubes to punters at £5 each all day long!
From a purely profit prospective, my local pub would be just as well off if they only opened Fridays, Saturdays, and Sunday lunchtimes as these are the times they make their money. During quiet times they will just about cover their wages & overheads but they open 7 days a week because the punters expect the facility to be there whenever they fancy a beer.