Yes, a luggage concierge can be tipped, which is where the real money is. Let's just say that people with demanding requests usually have demanding money. They've learned that money talks, so throwing an extra hundred at the concierge to ensure that your bag makes it safely on the plane is worth the money. That kind of money adds up, and it isn't too bad of a job considering you're already getting paid to ensure people's requests are taken care of.
Of course this isn't a blanket true statement. If you find yourself working at an airport or airline that isn't busy, you may not make the same money, but that's also true for someone working as a bartender at a bar. If you're looking to work in the airline industry, this may be a better bet than the more illustrious positions like being a pilot.