I can certainly understand the anger of the GP, apparently roughly 25% of the Croatian citizens do not live in the country. As an expat myself, having a say in how my home country is run is nice, but I feel it's a bit "easy", because I mostly do not have to live with the consequence of my choices.
Lol, that's considered "conservative right" ideology in the USA.
The expats usually left because they didn't like the strictures or ideology of communism. Some had property confiscated and/or were harrassed by the authorities for whatever reason. Most of these people have a reflexive aversion of the left and are reliable right wing voters.
Those who stayed seem to be those that agree with communism to whatever degree, who were part of the communist regime in some way or those that did not mind or did not have the means or will to leave. Some have been indoctrinated to some extent, or maybe more correctly they have grown up in the culture of that time.
Many ordinary people suffered from a relatively poor quality of life under communism. Croatians received a relatively smaller share of resources and opportunities because of Serbian dominance of Yugoslavian government.
The differences are not all or even mostly political. Many locals just resent expats who avoided the misery and show up with money and a particular attitude, usually a critical one as to the dysfunction and corruption in Croatia, amongst other criticisms.
Full disclosure: I'm an expat (who lives in Croatia, for now), so that may colour my view.
The other extreme is what we currently have in Croatia:
A vast group of people who don't live here have citizenship and they express their patriotism by voting for the conservative right without exception for the past 30 years.
If you want to be treated as a citizen — live here and pay your taxes. If you don't, the door's that way.