Try not selling.
You will find yourself outside the offices of the company which you founded and grew without outside capital , screwdriver in hand and an attorney at your side, jimmying open the locks because the investment bankers you tried to fire had the locks changed. Your newly hired comptroller, selected with input from the bankers, will stay on for a few weeks, leaving you a note with "do not try to track me down" in the last line, and he will turn up along with the majority of your employees in a firm you had declined to purchase because its booked business was bogus. Because Mary Jo White is the United States Attorney for your district, no one worries about prosecution. True story.
Rarely have I met with a venture capitalist who did not start trying to deal out my other shareholders within five minutes of an introduction.
In the end, business is about cash-in exceeding cash-out, a condition that can be met one of two ways: 1) buying an interest in a firm and selling that interest for a higher price or 2) selling better stuff for a lot more than it costs you to create. 1 requires a lot less talent and discipline than 2, and not just because investment bankers don't have to take returns from disappointed customers who bought their hype.
If SnapChat's founders really made this call, then they are toast, but I doubt it. They are following the guidance of investors. Most likely, declining this offer enables them to use their now highly-inflated shares to acquire other assets, trading movie-set houses for real houses.