Buying stocks on election night when Dow industrial futures briefly plunged by 800 points was a "no-brainer," billionaire and Icahn Enterprises Chairman Carl Icahn said on CNBC's "Power Lunch" on Thursday afternoon. 

"I feel I didn't buy enough," Icahn said. On election night the avid Trump supporter said he left the post-election celebration around 11:30 p.m. to buy stocks.

Before election night everyone was saying that if Trump won, then markets would crash, he noted. But that was "nonsense" because Trump said he was going to do a lot of "good stuff" like lower taxes and roll back regulation so the odds were "tremendously" in his favor that night when he bought up stocks. 

That initial drop in the Dow was "completely, totally insane," but it let him "play the market," Icahn said. "So I tried to and I did buy a fair amount, but not nearly what I should have."

The number one thing Trump should focus on when he's in office is changing up the regulatory agencies just like you would do with a company that's "terribly run," he advised. "What's happened over the last eight years is companies are afraid to invest because they're afraid of what is going to happen if they invest." 

So far, everything Trump is doing should lead to a "much, much better economy," Icahn said.