There is no way Twitter couldn't turn a profit on $2B in revenue. But that's not their focus at the moment. Instead they really want to grow the revenue numbers even higher, worrying about the profit later. However they may not be able to increase revenue much higher, and investors aren't really interested in a profitable but stagnant Twitter. But if they wanted a profit they certainly could, starting by right sizing the company rather than pouring hundreds of millions of dollars into R&D that is barely moving the needle.