Here's the official Medium post by the cofounder, in which there is confirmation that they are returning the money to investors: https://medium.com/secret-den/sunset-bc18450478d5 The post also includes the phrase "incredible journey" verbatim.
Was that a reference to this tumblr: http://ourincrediblejourney.tumblr.com/ Pretty appropriate.
> Companies go broke all the time. It’s unfortunate and it may mean a service you love will close. But some things just don’t work out. [...] This is what is galling. A company that can afford to pay millions for some new staff but not for what those staff built. The people who used the service, and invested their belief and time in uploading photos, or forming friendships, or logging data, are left to find new virtual homes while their former hosts enjoy a nice (if possibly delayed) payday.
-- http://ourincrediblejourney.tumblr.com/post/89180616013/what...
Although admittedly, from an end-user's perspective, the effects are the same no matter the reason for the shutdown.