There are no free lunches on the internet, article.
...the thing to note is that the business model of all these free services involves exploiting what they know about you. Or, to put it more crudely, if you use "free" services then what you have to accept is that you (or, more precisely, your identity) are their product.
The penny drops for most suckers, er, users when it occurs to them that the service is, somehow, becoming more intrusive...
I find it interesting that investors will continue to pour money into companies which month after month, year after year have ever-growing and huge expenses and no income in sight. Apparently enough people will bet that if a company becomes big enough, some kind of profitability is sure to follow eventually. I guess we'll learn more about how that goes.
But interestingly, I doubt Twitter (not that I value it a lot, as you know) would have become a world-wide communications phenomenon if it had not been free. 90% of people just find "free" to be an intensely attractive thing. Many find it essential, and will work for free for hours to get something "for free".
It's just about impossible to imagine Twitter disappearing by now. But if it never finds an income source, then what?