Answer:
He didn't exactly "hide" them. In the movie Schindler's List, he starts out wanting to buy an enamelware factory so he can continue his lifestyle of money, wine, and women.
Schindler hires Jews because his account, Stern, tells him, "They're cheaper than Poles." Schindler didn't want to spend a ton of money on workers, but after seeing the ghetto being liquidated (emptied) and the horrible, nauseating treatment Amon Goeth bestows upon the Jews, he begins to find ways to bring as many Jews into his factory as he can.
It's a really great movie, and it really helps you understand the Holocaust from a different point of view. I would suggest it if you're interested.