He doesn't have to, the Ryanair booking algorithm already screws you for every penny.
At the very outset, when you're interested in a flight and come back later to actually book it (perhaps within the same hour), their system knows it's you again, that it has you 'hooked' and will ramp up the price for no good reason. Or, you're late to the game and there's not many seats left now, so the price goes up because they know they're going to fill the plane and they have you over a barrel.
I guess the latter is normal and all carriers will do that, but I have experienced the former and I think it's really shitty.