> Don't want to invest my time into something that will eventually sell out

And what do you think the gentleman behind Signal is out there for?

His modus operandi:

* Start a company, call it something catchy, like Whisper Systems.

* Get media coverage and some users.

* Sell to Twitter

* Start a company, call it something catchy, like Open Whisper Systems.

* Get media coverage and some users.

* ...

Start to see a pattern? :-)