Goretzka, who completed his move to Schalke from Bochum yesterday, said that he is keen to keep himself "grounded" however much he makes.
"My whole family is down to earth and helps me to stay grounded," he told Bundesliga.com.
"I try hard to remain the same person. So far, no one has said that I've changed. I play football because it's fun; I don't play to make lots of money."
The 18-year-old has been capped by Germany at Under-19 level.