My vaxxmaxxed ex-husband now has COVID for the second time. When I finished laughing at him and read this, I got a little worried. He had the coof for the first time last winter and had a pretty easy time of it--not many symptoms, just had to stay home for 5 days because of The Rules. It wasn't a big deal. However, this time he is a good deal sicker, which seems like it shouldn't be if we have a virus that is becoming more transmissible and less deadly. (I am a pureblood and have also had the coof twice. The first time, during delta, was moderately miserable; the second time, during omicron, was just a whole lot of fatigue.)
So what you're saying about things getting worse with the boosters and the vaxxed people's immune systems is plausible according to my anecdata.