I'm not sure I believe your factoid. Can you cite? UHC is one of the wealthiest companies in the world.
Health insurance does have profit caps, so like the sibling commenter said their margins are small (6%) but also decently under the cap (20%) in the first place.
their september 2024 earnings put them at 6% margin. that’s not very good. for reference apple is 15%, mcdonalds is 32% and costco is about 3%. that being said compared to a competitor, elevance at 2.5%, they’re doing well. a little worse than allstate (car and home insurance), which is about 7%.