Or to put it another way, people care more about money than their own privacy.

Yep. I have a limited amount of money that I need to spend on more essential purchases. I'll happily trade my data/privacy for the right frivolity.

When someone starts letting me pay for groceries with my browser history sign me up.

If your browser history consisted of you shopping for groceries, would this be a self-paying system and eternal free food?

Good idea isn't it?

That would be thousands of dollars a year in value. Do you happen to have anything to offer besides your browser history? An email list perhaps?

For the right price I'm okay. I paid Netflix for an account but they use my data to train their algorithm and enhance their product. I don't know all the details behind their work. Am I not trading their privacy? Do I really know if they aren't selling my data my preference with another partner? Do I want to pay $$ for social network? I have to weigh what justifies cost for me; most of my friends won't pay for an account for Facebook, and because I enjoy having an online social network with my real life friends, I am okay for as long as Facebook doesn't sell my name to advertiser (they can track my browser history for sure and I know they do). I accept the risk and I keep a close eyes on my online activity so nothing backfires on me.

Don't think it's really about privacy in this case. I mean how can anyone seriously be a Twitter user and caring about their privacy.

Would be like standing in the town square screaming your thoughts into a loud speaker then being upset that everyone knows what your thinking.

Personally, I always wanted to see a site that has ads and is free to read, but charges a small fee to create an account - just to see if it would help reduce trolling and sock puppets.

Do you mean something like Metafilter? [0]

Anonymous users see ads. Authenticated users don't. It costs $5 for an account.

They have run funding drives but, to date, $5/user keeps the lights on and provides a small crew of moderators each a modest stipend.

[0] http://www.metafilter.com

Edit: spelling, grammar.

Or The WELL, which has the best interface hands down of any social network -- but it's filled with a homogeneous paste of same-aged, same-politics, same-favorite-Dead-live-bootleg Classic Nerd-Hippies.

SomethingAwful does this, it works.

Some variant of Sturgeon's Law?

Not necessarily. I'd make some comment about people's price elasticities (or maybe "people overvalue free"), but I'm not exactly sure what it would be.