Not OP, but because I could flip a switch and get an extra $200/mo for doing nothing extra, at a time when that was important to me.

When every other site on the Internet seemed to have banner ads, the moral quandary was whether I wanted free money or not. That was an easy decision.

Not sure what kind of reply you're expecting here. I'm defintely not cheering you on for abusing users to make you $200/month. Your business model is cancer and the reason why the Internet is the kind of shithole it is today.