Why are they so fixated on despising Whites because of muh colonialism, muh racism, and muh White privilege that they would have to resort to blame Whites for what kikes in Israel are doing?

It's a product of postmodern Cultural Marxism, which is usually known as SJWism in normalfag circles. They're basically so bad, not even some liberals and some modern commies like them. They're not even hiding the fact that they want White genocide. However, they do seem to be just merely paper tigers at times. The reason why you think they are being arrogant and ignorant on many certain things is because they have massive amounts of inferiority complexes that they can never conquer. Remember that SJW book known as "White Fragility"? It reeks of pure projection and virtue signalling. They're incapable of feeling truly superior to their enemies, because they always feel the need to complain about how "oppressed" they are or how they're being "harassed and attacked" by mere words on the internet. Free speech only matters when they want to say things, it's not free speech when other political views want to have a say. Instead it's "hate speech", they're practically Bizarro neocons.  

Leftoids don't understand that Jewish revolutionary politics require tipping the scales at both sides. There are no drawbacks to having communist fiefdoms for kike bankers/international capitalists.

White europeans are the main obstacle to their conquest because historically, Christendom has been at odds with Jewry (most sects of Christianity are thoroughly kiked now, though). Islam has been subverted for far longer than Christianity. Muslims obviously don't like Jews that much, but that doesn't stop them from being useful politically to Jewish interests (see: migrant crisis!).

Jews historically have often fought alongside Muslims against Europeans. In a broad historiographical context, one might argue that the migrant crisis being manufactured by Israel is a modern iteration of said phenomenon. At any rate, Christemdom is laying on its back and Jews and their European political lapdogs have opened the floodgates for millions of them. They realized that there would be many opportunists who would flood in to Europe despite not actually coming from war-torn countries.

Christianity (and in particular Catholicism) was what kept Europeans unified against Jewry throughout most of history after Christ. There was a time when kikes actually got expelled from European countries. What happened? Many of the yids who were expelled from other European countries (in particular, Spain) fled to Holland and started practicing mercantilism (slave trade came along soon after). The Reformation happened and Calvinists introduced the practice of usury in lending: Christians began acting like kikes. In more modern times (late 19th century) the Schofield reference bible got published, (which, along with the outcome of WWII sealed the deal for how most Christians felt about Jews). By WWI the Rothschilds had accumulated enough wealth to further the goals of Zionism to completion (see: Balfour declaration).

In short, with the dissolution of Christianity as the primary bulwark against Europe getting fully cucked, a difficult problem facing the modern far right is finding another point of unification; there is so much disagreement on points like religion that forming a cohesive movement is heavily hampered. Identity politics on the right-wing of the political spectrum really seem as insurmountable as those on the left, although they are obviously different beasts.