For a long time I didn't understand how sites like Facebook and Youtube made any money because I have so much adblockplus/noscript/FacebookContainter/GoogleAnalyticsBlocker/uBlockOrigin on my FireFox browser that yeah. I just didn't understand.
The worst ads imo are for VPNs. I simply have to laugh at how their only major marketing tool is "you can watch region-locked Netflix".
This guy explains it all (lots of videos with people trying to explain VPNs on Youtube, but this guy nails it.
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The statement at 4:50 makes me laugh.