Spain discovered massive gold and silver mines in Peru and Mexico during their conquest. They brought massive amounts of it to Europe as well. It didn't make them fabulously rich, it just created inflation. The Spanish peasants and elites didn't grow richer. In fact, in terms of economic affluence, they languished far behind their English, Dutch, and French counterparts.

Those countries had no such gold reserve but they produced more wealth i.e goods and services. They had more economic activity and produced more food, finished products, luxury goods, and raw materials. Thus they were wealthiers.