Your "investment" doesn't obligate Mark Pincus into answering a stupid email. You gave them money entirely out of self-interest -- a gamble that you would somehow get more money back -- and they spent it. There are all of the answers you deserve.
The directors do have a fiduciary responsibility to their shareholders. It's reasonable for an investor to expect directors not to waste money.
His investment did not go to zynga, it went to whatever market seller he bought it from. He is more accurately a shareholder - a part owner - rather than an investor.
It is difficult to imagine this email getting a response though.
Assuming the investment was bought on the open market, Zynga probably didn't see a penny of it (though it might have helped to raise or stabilize the stock price in a miniscule way).
So Pincus doesn't have any reason to even read your email, much less respond.
