I am also from NL, and first of all, you are blaming a big and diverse group, the 'left', for unnuanced statements and regrettable actions of some individuals. Every group has its crazies. Doesn't mean the whole 'left' is like that.
Second, they may be right. Which groups with 'different opinions' are you talking about? Geert Wilders has been convicted for libel against ethnic minorities. And Baudet has said that he wants Europe to be mostly white [1].
Third, now overgeneralizing myself, the 'right' does the same thing too: calling people on the left 'profiteers', crazy and lazy hippies who wanto to avoid any labor, etc. In fact, you are blaming the political left in your post right now for the murder of Pim Fortuyn, based on vague and unsubstantiated claims. You are doing the same thing you blame the left for.
And lastly, the original ideals from the left are very much needed in this neoliberal climate where the rich get richer and the poor get poorer. The economic divide is growing. Even the VVD is moving towards the left, seeing that the capitalist race has gone too far. One example: the Netherlands has a very serious housing crisis right now caused by neoliberalism. From the credit crisis to selling and reducing out the social housing stock, investors only wanting to build high end apartments, etc. In the last debate about it, the VVD was advocating for a bigger role in housing, that ideal is tradionally associated with the left.
So please, don't polarize, overgeneralize and blame the whole left for murder and name-calling. Using your line of reasoning again, it is not like the 'right' is in a good place right now with their corona denial and Qanon conspiracies.
[1] https://www.ad.nl/politiek/baudet-verliest-zaak-tegen-buiten...