In countless Christmas movies, we get the impression that the elves of Santa's workshop are happy, joyful people who do all their work for fun. It's part of the myth: who would want toys from a man who forces elfin creatures to do his bidding only to then give away all of their hard work to strangers and force them to start all over? The more you think about Santa, the more I realize those elves are his slaves.
(1) Santa has no income. Maybe all those fake Santas which crowd the malls bump up part of their paycheck to the big man (think of it like a franchise), but that wouldn't be enough to cover the cost of materials, let alone labor.
(2) There's no way that the North Pole is the elves' natural habitat. They don't have the fur needed comfortable survive there. Typically elves live in the forest. Now, obviously, Santa wants to be isolated from the humans which is why he lives in the North Pole. But there are plenty of other places he could be, places more hospitable for his elves (here's a map of the world based on how long it takes to get to a major city). The Amazon is quite isolated, as is the Sahara Desert. The Himalayas are warmer than the North Pole if you don't go too high. All are viable candidates. But Santa picked one of the most inhospitable places on the planet for one reason: to keep the elves indoors. If he was in the Amazon, in a place they were comfortable in, they might run outside instead of working. Not only did Santa kidnap them, he's trapped them in a work camp.
(3) But if they like to work, then it's ok, right? Well, if they like to work, why do they need Santa? Why not just stay in their natural habitat and send toys out into the world? Hauling cargo is work, too. Yes, they won't have Santa's magical powers to deliver them all on Christmas Eve, but so what? Unless you're talking about something that could spoil or die (which accounts for a tiny fraction of presents), they can be delivered weeks or even months in advance. It's more likely that after Santa kidnapped them, he lied, claiming the presents had to come out on the 24th and only the 24th, thus "justifying" the kidnapping.
(4) But what about all the shots from movies and television with the happy elves? For one, that's fantasy and you're mistaking what's fake for what's real. (Grow up, seriously.) Besides, Santa's an all powerful being (which brings up the question of why he doesn't make the toys himself): he brain-washes them.