Turns out when you create content specifically to piss as many people off as possible, so you get rage engagement and make an assload of money, you also end up painting a huge target on yourself, which is pretty unwise in a country where literally anybody can just go out and legally buy a long-distance assassination-tailored gun on a whim.
2015 a man got into a domestic dispute with his wife. In response he killed her and his own three children. Then he set the house on fire and shot himself in the head. Later, “anti-government literature” was found in his truck. Any sane person would call this a horrific act, but it had absolutely nothing to do with this lunatic’s political leanings. Nevertheless, this instance is one of many like it counted as a “right-wing extremist killing” in the statistics you cited.