You also have to remember they are owned by Planestation who own Manston airport. Therefore the airport and the group as a whole profit from the landing fees charged on the tickets as well as from concessions(car parking/retail sales etc).
So even if Eujet make a slight loss this could be offset by the profit to Manston (not sure if Manston are making a profit on this deal I suppose that depends on the load factors as well).
But realistically you could have a point whereby the group profits more from 20,000 passengers paying £10 from a ticket than 10,000 paying £25 a ticket.