Billionaire Ron Baron expects mind-boggling returns from Elon Musk-led Tesla

Buy-and-hold investor Ron Baron expects Tesla to continue to take off

Ron Baron, famous for buying and holding stocks for a long time, sees big things from Telsa through the next 13 years.

"I think that in 2020 we're going to make from present prices about four times our money," the billionaire founder of Baron Capital told CNBC's "Squawk Box" on Wednesday. "I think in 2025 we can make another triple, and in 2030 it can be another triple."

The 73-year-old Baron explained how he amassed a stake in Elon Musk-led Telsa worth about $300 million. "We have brought shares of Tesla, about 1.6 million shares over a 3½-year period of time. Our average cost is about $208 a share." Shares of Tesla closed at $280.98 per share on Tuesday.

While painting a long-term bullish scenario, Baron declined to reveal his recent moves in the stock. "I can't tell you what we're buying now. We report once a quarter."

But making a case for why Tesla's $2 billion acquisition of SolarCity in November makes long-term sense, Baron said it comes down to the capacity of the power grid.

"Forty percent of the electricity in the United states is used by single-family houses," he said. "If you put a [Tesla] car in the garage, that car uses 30 percent of the electricity of the house."

"In order to sell the [electric] cars you have to ... have an increase in power," he argued, saying the proliferation of SolarCity's solar solution products, such as panels and special roofs, can pick up the slack.

Musk is chairman and CEO of Tesla and was chairman of SolarCity.

Baron also said Under Armour stock was "cheap" after losing about a quarter of its value since Jan. 31 on weaker-than-expected quarterly results and a warning about the future. He expressed continued confidence in UA founder and CEO Kevin Plank's ability to get back to robust growth.