It's obviously difficult to sum it up, but there are two main factors that come to mind. The first is the economic situation you mentioned, along with the fatigue that comes with the feeling of working a lot but still not being able to afford much. The second is a general feeling of distrust in the government and politicians, a sense that you're being ripped off by corrupt politicians putting money into their own pockets, and a lack of hope towards any of that getting better.
The knowledge that these problems are not as painful in more modern nations such as the US or Switzerland contributes to a feeling of "being left out". Not that the problems don't exist there, but the less you have the more painful they are. For example, old people in Romania often live on a pension of almost literally nothing.
I don't want to paint too gloomy of a picture though. There are definitely worse things than walking around Bucharest's old town with friends and a shaorma. :)