I've been aggressively blocking online ads for 25 years. Why? Because they are all crap, that's why. I have never seen an online advertisement that had any bearing whatsoever on my life. That's not once. Ever. So why should I waste the bandwidth?
Every now and then, I'll drop the blocks for sites such as ElReg. If the ads were sensible, weren't lies and/or outright fraud, were relevant to my needs, and didn't constantly fight each other to get in my face, I'd probably leave 'em be and simply ignore them. But they aren't. So I reset the blocks after a day or three of gritting my teeth ... and I'll continue to block them for the foreseeable future.
And of course there is the problem of ad-delivered malware.
Honestly, who do the ad agencies think they are fooling, anyway? That's rhetorical ...
 Really. I started blocking ads with a simple HOSTS change in '94 ...