Mr. 金牌 confessed Belle he did not bring magic back for revenge. Why do 你 think he did it then?

To find his son.

I think to balance out the power for his own gain.... While he is marvellously sarcastic and we all 爱情 him, he does 爱情 to be in control 或者 at least in a position where he can seize control. And the magic may help him find his son which is another reason I think he did it....