Totally shitty behaviour. Know someone at work who has done this and he’s a total dickhead.
Most holiday companies work on fluid / demand based pricing too so by having a reservation you probably won’t use, you’ve driven the total cost of the holiday up for everyone else. We automatically price up when a set number of each cabin grade are sold and then it only goes up from there…until a load of people cancel and we have to desperately hammer the late market, which is also shit because the people who booked early in good faith miss out on an even lower price because we have beds to fill. The shittiest thing about that is that everyone then goes on the same holiday…you haven’t booked early, paid more and got something extra. It’s like playing the stock market.
In short: capitalism sucks for everyone.