What AmieLee said was right, however, the way I see it, Victor does not want to "rob" Walton of his ambition, rather make himself (Victor) an example of, as Victor shows how careless ambition (doing it 'because you can' or because no one else has done it before) can destroy the creator.
Walton is sort of the same sort of personality as Victor, unwaveringly ambitious, and the position Walton met Victor (the expedition was getting dangerous (getting stuck in ice and he was wondering if he should keep on going, or return home)), Victor was able to tell/warn Walton that ambitousness can destory, which is the overall message Shelley leaves with us