Mark is performing for television. The only appropriate response to a 30 second offer is "f--- off".
That, and most of the deals he (a Billionaire) is talking about investing in on Shark Tank involve him doling out incredibly small and insignificant sums of money for equally small and insignificant (in his eyes) returns.
He really doesn't care if you take the offer or not on Shark Tank, because even if you do and you succeed beyond your wildest dreams, it's not going to make him any richer than sitting through a Dallas Mavericks game would.