Yes, the vast majority those elites did not profit, either in an economic (they mostly owned land, not corporations) nor more important (they / their sons were dead) sense; something like 1 in 4 young men were killed.
Even at the turn of the century, the foundation of the wealth of the British aristocracy rested on ownership of land, agriculture, and control of the Empire. The Great War disrupted all three greatly.
It was mainly the merchant and upper middle class that owned stocks, ran businesses, and profited from the war, with a tiny fraction of aristocrats benefiting.
Most of the rest saw the value of their land go towards zero, their manors used for wartime purposes while their servants were conscripted away, their sons killed on the field of battle, and confiscatory tax rates imposed to help fund the war effort.
This pattern was repeated again in WW2.
There's a reason Downton Abbey is set on the eve of WW1 and goes into the interwar period — that's when the British aristocracy was systematically taken apart piece by piece.
Common people largely supported monarchical, aristocratic governments before WW1. One reason was because their elites that actually put their money (and their lives) on the line for their nation... although sometimes with disastrous consequences.
Note that historically, the world wars were when wealth inequality dropped the most quickly. The US raised marginal tax rates to 90% during WW2, and most wealth was real assets, which obviously suffered greatly all throughout Europe. In a total war, everyone can give up their lives, but the wealthy can also lose their wealth.