A remember a very, very, very high % of flight technology (basically flight school) majors in university being in ROTC. Paying for fuel is additional to tuition and it was extremely expensive. A lot of middle and lower class who wanted to be commercial pilots joined the military to get it paid for. No idea how many became fighter jet pilot, I assume most of them got jobs doing something more boring like troop or materials transport.

I would go so far to say as commercial flight is dominated by very rich people who could afford to do the commercial ratings on their own, or middle/lower class people that became military pilots to pay for it.

Very few rich people become commercial pilots. They might get a private pilot license as a hobby but generally pilots are just employees they hire to take them around.

Plenty of working airline pilots come from regular middle-class backgrounds and never served in the military. They take out student loans to pay for training, then work low-paying jobs as flight instructors or something to build up enough flight hours to get hired at a regional airline.

Those who go the ROTC route can totally get a fighter jet assignment if they want it. Once they get selected for a pilot slot, assignment to a particular airframe is primarily based on how they perform in the training pipeline.