I have a follow-up question, if anyone can answer. Was it possible for a non-citizen under Roman rule to be wealthy and have a luxurious lifestyle or was that only possible for citizens?

This is a tricky question with no set answer. The most comprehensive, easily accessible study I know of is by demographer Walter Schiedel, who concludes that the peace and economic development brought on by the Roman empire had the paradoxical effect of decreasing quality of life, because of overpopulation and a greater communicability of diseases. This overpopulation would have led to decreasing conditions in the countryside as peasant were no longer capable of effectively negotiating their position, leading to effective serfdom and the general replacement of agricultural slavery with cheap free labor, as described here by Elio lo Cascio.

This Malthusian interpretation is one among many, but it is interesting and more reliable than the simplistic civilization=good, barbarism=bad seen in other responses. A much more extensive set of osteological and other evidences are required to give a more definitive answer, however.

The "Roman Empire" spanned across continents and centuries. It is hard to say who the "average Roman" was. The empire was also a political patchwork of provinces, territories, and semi-autonomous states, all having vastly different relationships with the central government in Rome.

Also remember that the territory you refer to as "Europe" was at the time a vast sea of peoples and villages without many centralized cities or states, as they are thought of now.

To try to answer your question though, usually the closer to the Mediterranean you are during this time period, the more likely you were to live in cities or generally have access to better infrastructure, technology, and trade.

EDIT: The question was asked in a Euro-centric fashion and I answered it as such. It is true that at the time many eastern societies were at least as advanced, and the rule of thumb I provided above relates only to the Occidental world.

After the edict of Caracalla, most non-Roman citizens in Europe were Roman slaves. Before then, most were either Roman slaves, freedmen, or residents of conquered territories. The residents of conquered territories generally had a lower standard of living than the residents of Italia proper. But, in certain instances there were examples of rich non-citizens - certainly, in the short term wake of the Roman conquest of Greece, there were plenty of rich Greeks who maintained their wealth but weren't citizens.

If you mean people who were not residents of the Roman empire, well, the thing is, Rome covered virtually all the well developed, agricultural areas in Europe at that time. Most of the places in Europe outside Rome were forested areas inhabited by nomads and hunter gatherers. Their standard of living was worse than virtually everyone in the Roman empire, besides some slaves (those destined for the mines to be worked to death, and such). The limits of Roman expansion into Europe, really, were the non-developed areas. They didn't have cities and such capable of garrisoning and supplying legions. Roman legions could march into these areas, beat up the inhabitants, and gain some cursory submission (like in the Roman campaigns in Germania), but they would have to flee back to the "civilized", agricultural areas as winter came to avoid starvation.