Most engineers at large Ad-supported companies are not working on ads in any meaningful way.
Ads pay the bills, but only to the extent that you have something people want, to put the ads next to, and most of the engineers are there trying to make something people want.
I've always felt that same way too. Lots of really smart people doing what they can to get more people to click on ads ... the source of 99% of their revenue. Seems a little sad. Same but less so with Google as at least they make $ from their cloud product ... whose development is funded by ad clicks.
Not at all. Connecting the producers and consumers is a field that's been changing in the most radical way for the last 15 years, and whole humanity has reaped enormous benifits from it. A lot of people I personally know started making jewellery, cakes, and other small artisanal items and selling them on Instagram. Quite a lot of others - importing small hiche items from China. Most of my friends started buying some items like that.
All these people got their lives improved thanks to engineers that enabled worked on selling ads. There's a popular stereotype that "ads" is some evil capitalist thing designed to manipulate you to buy some shit you don't need. Looking at the world around me, I see something different.