I'm missed out on a bunch of profitable tech booms just by a combination of being lazy and by feeling that things like domain scalping are somewhat inherently immoral.
If it's any consolation, it was only profitable because not enough people thought to squat on them so enough of them were turned into sites that made the web interesting enough to become massively popular. I tell myself such things, anyway. :)
I prefer the term "Domain Scalper". As it so happens, domain squatting is a legal term and it refers to buying the domain of a registered trademark just to sell it to the owner of the trademark. It doesn't even have a good resolution rate either.
Someone else made a comparison to phone numbers which turned out to be accurate. Simple sells.