Well not everything, we're talking about encrypted mail services. Skiff being acquired proves that there's a market for buying and selling such a thing. And if someone's interested then Proton should be an even more attractive target (albeit more expensive):

It's a startup, so it will look for an exit at some point. It has built a large user base and good word of mouth. It's currently working on locking down the ability to take your mail elsewhere.

It's ripe for plucking and squeezing and it will happen sometime this year IMO.