With all this gold, Spain went on a buying spree, weapons, art, churches etc - and the sellers(rest of Europe) industrialized as the gold trickled down into THEIR economies. When the gold no longer arrived, Spain went into a steady decline as their rich upper crust of RC Churche, Kings, Queens, Lords, Ladies etc. and eventually became democratic after Franco.

Primarily spent in wars (mercenaries, weapons, warships...) and keeping the colonies under control.

We were democratic before Franco. Twice. Until the damn conservatives threw the Republic down, twice, too.