I fail to see how. If you are compensated at the market value of your work, that seems fair and Mailchimp gave generous compensation.

You could argue that the gap between wages and capital gain has become too big, a point on which we will be in agreement but to be honest with you, I think the surprising part is that someone would want to pay 12 billions for a company with $700 million of revenue. Still I have found the market to be surprising for a long time so maybe it's time I reassess my expectations.