Why all against Greta Thunberg?

In recent weeks the media populists seem to be enraged against Greta Thunberg, the little girl who every Friday on strike to stimulate some action against global warming by governments. In itself it is successful in its intent, meaning they had a lot of attention, with the exception of countries (such as Italy) where state media are already in the hands of populists, and then try to limit it.
But why populists are investing so much energy in groped to defame, and why they rant against her, going to control what they eat on the train, and unleashing at any fake news are able to imagine?

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