I had the pleasure to work with some of them in my ad network days, and I can see why they achieved what they did.

A crappy “news” outlet talks about disgruntled employees that did not like the fact that they did not get a big exit but it is my understanding that they were compensated with salaries over the average, which was always known about and employees agreed to it. My previous experience with startups is that almost NO ONE is willing to trade a discount on their salary and effort for equity.

Would I use Mailchimp today? No. Anyone running a company should avoid SaaS as much as possible. I can only recommend to use sendy.co to pay 1000x less for any email communication.