Antifa has been around for a long time already, the main difference being they becoming more visible in America now given Donald Trump. In Europe and elsewhere where a tradition of rioting is more persistent, antifa and even non-political groups like sport fans riot and engage in street battles because that's what they do. In America, the 1960s was a very violent time before Antifa as the media thinks of them to be even existed during the struggle for civil rights and the peace movement against Vietnam where people were being killed, by both the government, KKK, and those against it. The FBI were killing Black leaders while the KKK were blowing up black churches, and people of color were fighting back, especially after MLK got killed. You had Kent State where the National Guard killed protesting students and you had Vietnam going on where people were being drafted and being killed in Asia. With all the shit back then, things were bad enough to fight back given how terrible the government was. Today in America, it seems that things are bad enough to fight back which some realize while others don't. The poorer are getting poorer, and likely they'll "legally" lose more power as the country under a minority-supported government erase measures protecting workers, slash funding to education and benefits meant to help the poor, and other things as it looks to wage war, conveniently increasing military spending while saying it will reduce government. During the Vietnam War with the draft, young men did not have four years to wait for the next election to make things right, many will likely be dead by the time that happens. In this country, many people can't wait for reforms to happen before their quality of life drops sharply.