• Billionaire investor Ron Baron has poured $100 million into Elon Musk's Twitter deal.
•  The Tesla bull was promised to make "two to three times" his money, he told CNBC.
• Baron said the bet on Twitter was predicated by his faith in Musk's leadership abilities.

Billionaire investor Ron Baron poured $100 million into Twitter during Elon Musk's takeover of the social media company last year.

In an interview on CNBC Tuesday, Baron said he was promised that he would make "two to three times" his money on the investment. 

"He explained when we made our investment that he saw that there was a lot of cost there. It was incredibly poorly run," Baron said, referring to Musk.

Since Musk closed the $44 billion acquisition of Twitter in October, the company has announced mass layoffs and warned on bankruptcy risks as advertisers continued to flee its platform. However, Musk tweeted on Sunday that while the company still has challenges, it is "now trending to breakeven." 

Baron said he decided to invest in the platform because of Musk's experience as an exec and his marketing abilities. Musk has a huge public outreach, garnering over 128 million followers on Twitter.

"He's the best-known man in the world, I guess," Baron told CNBC. "Everyone else spends $1,000 to market a car. He spends nothing, because everyone knows Twitter."

The long-time Tesla bull added: "He spends nothing because everyone knows who he is."

Meanwhile, Baron remains upbeat on the EV maker despite shares being down 35% in the past year. He has been an investor for nearly a decade, with a combined stake of roughly $4 billion.

Baron expects that Tesla will eventually surge to a $4.5 trillion valuation, a 625% increase from its current market cap of $623 billion.

"We have made a lot of money with [Elon]," Baron told CNBC in early November, adding that Tesla holdings make up 40% of his Baron's Partners fund.