Hugely profitable - I think not
A company selling for $25m after $18.8m investment (according to Crunchbase) is pretty similar to having had the investment written off for a VC like DFJ.
The company had massive ambitions, but it seemed recently that they were struggling to deploy into whitespace hence the Weightless-N standard in ISM bands (unlicensed) announced recently. Being picked up for pocket change is unsurprising given that recent announcement.
Some big bets don't work, or don't work in time. Good on them for trying, and maybe Huawei will be able to bring it to market.