They do. It's not the only factor, since it depends on the type of antibody and how specific that antibody is against the variant it encounters, but as long as they have some neutralization ability then the antibody levels correlate to infection risk.
I think that's not unexpected if boosters give 70% efficacy against symptomatic infection by Omicron, and 35% efficacy from two doses. Even when the mRNA vaccines were around 90% effective against symptomatic infection with the virus dominated by the earliest variants, we would see some breakthrough cases. Back then I said that being vaccinated should be a reason to feel safer, but not a guarantee against getting sick.
I'm boosted but still being thoughtful about what I do -- avoiding crowds, wearing a mask in indoor public spaces, not getting together with multiple households simultaneously, etc. As always it is the case rates and their trends in my area that determine how I behave, and not so much my vaccination status, which I view more as like a safety net. Right now my county is around 26 cases per day per 100k people (barely into "very high risk" by the CovidActNow metric), and relatively flat over the last 3 months (if we smooth the squiggles due to holidays). We've been having a death every couple of days on average, with a population size of 229,000. Most of them were unvaccinated people.
Expecting to see a big wave of Omicron here before long. Have had 1 known case in the county so far, but there are bound to be many.