What is more surprising, perhaps, is that this is a claim that nobody else can make. But when you examine it, it is in the nature of democracy that there is regular turnover of those at the top. This happened in Britain, France and the USA. And the various non-democracies involved all had changes of government between the start of WW 1 and WW 2, which again results in turnover of those at the top.
So he became very successful. Whether this was because of, or in spite of, his mother's disappointment is another question. (I would be inclined on general principle to guess "because of", but I don't know enough for an educated opinion.)