It's not just (or even mainly) about 'relevant' ads
If you say you don't want relevant ads, why do they still track you?
It's about amassing as much personal information about you as possible, in the hope and expectation that they will be able to make money out of it.
And for an ordinary person it is almost impossible to avoid.
Stopping tracking and privacy-busting scripts in a browser will break some useful sites. If your friends and extended family use Facebook to keep in touch, and all their friends do the same, you can ditch it yourself only at considerable social cost. And my most recent example: not wanting to use gmail as a backup to my independently hosted mail, I tried my ISP's email, only to find that it's Yahoo and I would have to accept an appalling set of anti=privacy terms and conditions to use it.