Per your link, they sold for $425 million.
The investors lost money.
That is not the outcome they were hoping for. However, their preferences did provide them downside protection which was, as I noted, their purpose.
1) Good Technology was valued at $1.1 Billion.
2) The investors lost money, but the employees lost much more.
-> This is the problem with unicorns.
You've completely missed the point.