I appreciate your engagement!
> The most compelling reason I've read so far is that because the US sells weapons to Israel, though I think there's some good reasons to sell weapons too so it's not all negative.
Some of it is also memetic: a couple of decades ago Tibet was the cause celebre, after that it was Darfur and recall Kony 2012. Issues become important because there's active conflict and human cost, and then people discuss the issues that are getting discussed. And then sometimes those become signifiers for larger issues, e.g. anti-system politics as whole, liberal hopes, or conservative culture wars.
I don’t remember all of how society has reacted to various issues but the protests and discourse around Palestine seem to be an outlier in terms of engagement. But that’s just my interpretation.