Since you are willing to pay $100/year not to see ads, you are probably the sort of person who is worth much more than $100/year to Facebook and its advertisers.
Wait, care to elaborate? I'd assume it's the other way around; people who don't want to see ads are probably less likely to click on them and drive revenue, no?
He's in a financial position to afford $10 a month for the relative luxury of not being served ads, meaning he has a relatively large disposable income, meaning he's the kind of person I would want to advertise to.
Ah gotcha, yeah that makes sense.
In addition, his disposition for avoiding ads likely means he is running ad blocking, and thus already minimizing his ad exposure. This presents a less crowded field where any ads he does see may have a larger impact on his buying behavior.