> who is taking these booster shots now?

People who would be at risk of serious harm if they catch it. At least that's how it works in here in Norway. See https://www.fhi.no/en/va/vaccines-for-adults/vaccines-in-the...

I hadn't since the pandemic was (more or less) over, but last November I got a booster shot, as people seemed to be getting more sick than before. I know someone who (probably) has long-term covid, and you definitely don't want to catch that. However, I always become sick the next day, so I'm not too eager to get it.