When you have grown up in the Communist regime of the former Soviet Union, started your business career importing rubber ducks and becoming the 12th-richest person in Russia thanks to owning an oil company, then being accused of "failing to demonstrate even a minimum amount of manners and education" is unlikely to bother you.
The criticism came from Renzo Ulivieri, the chairman of the Italian Football Coaches Association who accused Chelsea of speaking to Italy coach Antonio Conte "without warning" about succeeding interim manager Guus Hiddink at Stamford Bridge.
Roman Abramovich, the Chelsea owner, is a self-made billionaire (OK, he probably had some help from people up high in Moscow). I don't know any billionaires, self-made or otherwise, but my working-class guess is that they are bothered about very little apart from where their next million is coming from.