Quite a lot of those people are "into" actual communism out of a mixture of ignorance and edginess. Revolutions sound great when you're naive. And it's not actually a great number of people as a proportion of the electorate!

The key is what happens to suggestions for "good tweaks". Do they get considered reasonably and implemented fairly? Or are people denounced for even seeking tweaks?

Flexible mixed-economy capitalism seems to be pretty stable. Capitalism that's blind to inequality produces an increasing long tail of disaffected victims with nothing to lose. Hence the rise of kick-over-the-table politics, epitomised by Trump.