Ads are also the thing that enables really amazing things to exist. Regardless of your feelings about facebook, the community it has created has had drastic impacts on the world at large. Almost the entire knowledge of humanity is now in anyone's grasp with a simple click of a button (Google). That was only possible because Google was able to make money off of it through ads. How do you propose that the internet pay for its self without ads? The whole freedom of the internet is because they can make money off of ads.
Not everyone needs to cure cancer to do something great.
What's deeply ironic is the modern internet is bankrolled by brand trademark monopolies, but programmed by a bunch of people who complain about government-granted monopolies...
There's a quote from the 1950's from a judge very skeptical of extending trademark law to the effect of "we shouldn't allow building brands too much, because then people will buy things for reasons other than product quality and that'll undermine competition in the marketplace by making products non-fungible."
I personally like monopolies,[1] so it's cool with me, but you have to wonder what the internet would look like if Adidas sold shoes and not "footwear experiences."
[1] There is no profit in perfectly competitive industries, and thus no money to do cool stuff. That's why, e.g., Microsoft is so screwed. It keeps hoping for innovation out of companies like Acer, Lenovo, Asus, etc, that have profit margins of just a few %.
'cure cancer' was just a placeholder for anything of greater importance to the human condition. However, maybe you are onto something. Maybe ads are indeed the lifeblood of the new interconnected, networked world of century 21 and beyond. I guess nobody figured out a better way to sustain life on the 'internets'. Yet...
Not everyone needs to cure cancer to do something great.