Also on my agenda, which is an interesting situation for me because I'm a heavy user.

I think it is a great way to stay up-to date on what happens in startup-land and in open source, the granularity with which you can follow people still fascinates me. Seeing that 95% of what active human accounts post is pretty useless, I don't see justification of a $20bn+ market cap, especially without growth.

PS: They've recently cranked up ads, next earnings report could surprise ...

I don't own TWTR, but that's irrelevant. All of Twitter's early investors are very pleased with their investment, while those who missed out or (worse) passed are probably wringing Twitter's hands. Anyone who invested $10K in one of Twitter's early rounds is now set for life. (If I could have gotten in on one of those rounds, I certainly would have invested myself.)

Current profitability is irrelevant. What matters is net future (discounted) profitability. People who malign companies for not currently being profitable apparently don't understand this, but investors do, and the market certainly does.

Many great companies are massively unprofitable while in their early growth stage, then become massively profitable in their later years, and are valued accordingly. If you can exchange $1B in profits this year for (say) $2B in profits next year, you'd be a fool (assuming current discount rates) not to make the trade.