Does advertising really work?
Everyone I know mutes TV ads when they come on.
Everyone I know uses ad-blockers online.
I avoid sites that say 'You can't view this site unless you turn off your ad-blocker.'
And some ads are so annoying &/or repetitive that I refuse to use the product on principle.

@Richard_Littler
It's like email spam. 99.9% of it just annoys someone to no purpose, but occasionally it finds a mark to justify the small per-unit expense.

And there's a meta-level scam, which is selling advertising is profitable regardless of whether the advertising works, and selling personal data collected by delivering the ad is profitable regardless of whether the data is useful.

The enshittification is self-fuelling at that point.

@petealexharris @Richard_Littler Software developers, on the other hand, tend to be paid primarily in equity, which means that their work (and compensation) is only valuable if their employer manages to sell it. The boss makes money either way.