all of it, including its future, was valued at $7 billion, but there was never $7 billion in cash. Maybe it was $700 million in cash paid for 10% of it, which would value the whole thing at $7 billion. If that totally-made-up 10% number happens to be the right number, then it hasn't lost much at all overall, but the investor who paid that has to share the sale price with a bunch of other shareholders who paid less. So, this owner lost money, but the firm did not necessarily.
(I'm not saying this is what happened, and maybe a quick google would get us closer to the actual numbers, I'm just saying you have to pay attention to the wording of what is being claimed; media likes to exaggerate.)
what has disappeared is "belief in the future prospects of this company to bring in profits worth $7B" which was why the last investors invested, and why the early investors set up the kitchens and other frameworks to support those hopes. And it's not that the opportunity wasn't a good one, perhaps a competitor "won", or perhaps there are too many competitors trying to share the $7B pie.