Yes, I participated in a clinical trial I only found though Facebook ads. Since clinical trials are very specific on who they are recruiting, it's a great use of targeted ads.

I also once bought soap that was advertised to me on Facebook. It's my go to brand of soap now.

I also read here on HN someone successfully using Facebook ads to target people planning on moving in their city to find an apartment before it reached the open market. EDIT: here it is, https://medium.com/good-signals/apartment-baiting-with-faceb...

Yes. Do you have an argument based on evidence, or at least reason, or are we going to continue like this?