When I read about the 2nd Punic War, I learn that the Barcas took advantage of the great wealth of Spain to pay off Rome and become very powerful.
When I read about the late Republic, I learn that Pompey conquered the spectacular wealth of the eastern provinces. And Caesar conquered the great wealth of Gaul. And Augustus acquired the tremendous riches of Egypt. The other day I even read about the great wealth of the island of Crete.
Doesn't the word wealthy lose its meaning when you use it to describe every square inch of everything? Isn't it a relative thing? Alabama is very rich compared to most of the world, but no scholar calls Alabama wealthy because its relatively poor compared to the rest of the country. Why does Rome get different treatment?
Why does Rome get different treatment?
You are talking about single persons getting access to the wealth of entire nations. If you got to plunder, extort and tax your way through Alabama you, too, would realize that its wealth is rather impressive.
Depending on whether you are talking about primary sources or not there also may be translation issues involved, e.g. opes is imo not inherently comparative as you understand "wealth" to be (divitiae might be more along your lines).
What defined 'wealth' as a term was a lot more broad than as you define it today.
In Ancient times, wealth included things such as: Money, the population, Structures, Land itself with fertile being the wealthiest of land, Resources from the land(Grain, Metals and Minerals, Silk and so on), Livestock and the list goes on.
It wasn't uncommon for a lot of places to have such things all together as you have mentioned and is why you read about them conquering spectacular amounts of wealth.