People who are anti-semitic and violent call themselves Proud Boys and Restore Britain.

It's true that a lot of radical leftists do "critical support" for Hamas, just like they used to with the IRA or ETA. But that's the same thing as the US government supporting Islamists against the Soviet Union and Reagan funding right wing militias in Nicaragua.

It's defending a resistance movement on some parts of their agenda even if you disagree with the rest, because you think they're fighting for a good cause against a common enemy.

Some Hamas leaders, individuals within the party, want to massacre Jewish villages to drive all Jews out of Palestine. Almost no one in the student protests was defending that. But when it's the other way around all the Western leaders rush to defend the Israeli government saying it's just two insane ministers in a big cabinet and the rest will talk them into submission. That's clearly not true when you see a lot of their ideas getting implemented.

If the conflict was just Israel against Hamas it would be one of the situations where everybody involved sucks and there's no clear answer to anything so you should stay neutral. But the Israeli government is treating it as a war against Palestine where they allow their soldiers to rape and kill civilians, you can hear generals publicly setting kill targets and "security" policies that were already close to Apartheid level are getting stricter every week. They see every Arab as a legitimate target.

That tips the balance to the point where you can argue that supporting any resistance, even violent nationalist Hamas, is the only right move.