You might be right that it's not an issue of conscious personal vendetta against migrants (although I wouldn't necessarily count that out) or an explicit class war, but I also don't think that either of those things are what most people (or at least not the ones who weren't just obnoxiously meming it for the drama or for hot takes) were trying to point out.
The comparison is meant to make us examine our priorities as a society. Why do we want to talk so much about these 5 rich people in the weird billionaire sub vs the migrant shipwreck? I do think it's a valid theory that at least part of it is that as a society we place more significance and worth in the wealthy white folks. I think that a lot of it is probably also a ghoulish sort of rubbernecking impulse. The details of the sub story were weird and a bit morbid. Neither of those impulses are great, and I don't think there's any harm in pointing out the inequities and inviting some self reflection on where they come from.
However, I don't love the sort of snide, gleeful celebration of the death of the folks on the sub either. I understand the frustrations that it comes from, but I think the folks cracking jokes or celebrating those deaths ought to be doing as much self reflection as the folks that were ignoring or ignorant of the migrant deaths.