I don't have a lot to say on this matter, so this may be an exceedingly short post. However, it's still something that I find absolutely atrocious. Even if you're not an antinatalist you should be able to understand to some extent I hope.
Tom creates a pig out of thin air because he's a wizard. No more explanation necessary. Who is indebted to whom? While you may at first think that the pig is indebted to the wizard, things don't necessarily work out that way if we think past our natural biases. The wizard cannot at once assume he has a debt to claim, and force the pig into a life of slavery and hardship (to pay for the wizard's retirement or look after the wizard when he is older for example). One one hand, surely sentient or near-sentient beings have RIGHTS and cannot be owned from the start by anyone! And moreover, if anyone is in debt here, it is surely the wizard, who took a risk on a life that was not his; he created the pig's life, so he is de facto responsible for any suffering the pig undergoes. Therefore HE is indebted far more to the pig than the pig is indebted to Tom.
What do I mean by this? Well what I mean is, the traditional practice of raising children to become moneymakers for the purpose of not dying alone and with money troubles is horrible. One, that's almost slavery. Almost. Two, surely something's gone wrong here - if anything the opposite scenario should take place! The only possible way you might expect a return from your children would be either (a out of love, biological love NOT BECAUSE YOU ARE A GOOD PERSON, or because (b you did not create them, but rather saved them from being parentless by adoption. And even then, they have rights. They aren't REQUIRED to do anything in return for your favour. You did not sign a contract with them. You forced it onto them.
And remember, forcing your dreams onto a child is basically the same sort of scenario too!
Take care of your children. Being a parent is not something you should be rewarded for, it's a responsibility. You signed no contract with the child saying they should repay you. It's also wrong if you're a biological parent, but you know the drill.
I can't think of how to edit this post, so I'll leave it as it is, a little rough around the edges. May come back to it later.