Yep, I -- an always very political, lefty, very critical person -- went down this trap. Nerd-sniped myself. Ended up working in ad-tech for some years and making pretty good money at it, and eventually ending (through acquisition) at Google because of exactly this. Because of intellectual interesting things... because of opportunity to do those things...
Copious quantities of impression data? Get to do big-data-ish things? Play with things like Cassandra etc (back then kinda interesting), k-means clustering and fun stats stuff and eventually ML?, high throughput & low latency transaction processing... shaving milliseconds off here and there... and lots of money in the sector... to hire devs, to do these things... which were at least back then somewhat intellectually challenging...
Especially for people not in the Bay Area, opportunities like this were/are hard to come by...
But then once you take a step back and look at how the sausage is really made, you start to feel icky.
Granted, that was ad-tech in 2010ish time-frame. It became much much worse.
Luckily within Google I was able to transfer out of ads, and into things that seemed on the surface much less icky (consumer hardware, etc.) But the thing is... no matter what you're doing at Google, that project is funded by ad-tech... So...