I think we currently are - but not because of online ads. :-)
My main concern is supply chain attacks. I'm afraid, the frequency and sophistication of such attacks will only increase, thanks to really powerful LLMs. From there - to running keyloggers and stealing your bank credentials etc.
"in-part because of ads" seems more reasonable, tbh.
When I worked at an adtech company almost ten years ago, this sort of shit was the exact concern of me and my colleagues. We've had time to do better but guess we're just fucked.