The biggest change over the past 25 years in terms of investing is that it's less expensive for the little guy, billionaire Warren Buffett told CNBC on Tuesday.

Buyers of stocks incur little in the way of trading costs compared to other investments like real estate, he said on "Squawk Box" after being named No. 6 on the CNBC 25 list of the most influential people in business over the past quarter century.

"Commissions are a lot lower than they were 25 years ago. Spreads between the bid and ask are less."

But on the other side, the commissions that professional money managers charge clients has gone up. "If you look at the fee extracted on Wall Street on balance, they've gotten quite substantial compared to 25 years ago," he said.

The Berkshire Hathaway chairman and CEO also said investors who put money into the 25 years ago have done very well, and will do so for the next 25 years—provided they don't sell.

Buffett is well-known for his buy-and-hold discipline. For example, he's held shares in the Washington Post for 41 years and shares in Coca-Cola for 26 years.

More on CNBC 25:

US doesn't have a rational tax policy: Welch, No. 12

The last 25 years: What's changed, who mattered...

How we chose the names

The List

No. 1 and No. 2 on the CNBC 25 list went to Apple's Steve Jobs and Microsoft's Bill Gates, respectively. "They belong there," Buffett agreed.

But the Oracle of Omaha saw omissions on the list in former Treasury Secretary Hank Paulson and his successor at Treasury, Tim Geithner.

"In 2008, our [financial] system was saved by a few people," he said. "We would be living in a much different country today had it not been for Hank and [Ben] Bernanke and I would say Tim Geithner, too."

Former Fed Chairman Bernanke did make the list as No. 3, along with his predecessor at the Fed, Alan Greenspan. The two men steered the central bank for all but a few months of the past 25 years.

Last week, Buffett told CNBC the U.S. stock market doesn't seem "too frothy," as some market watchers have suggested.

Berkshire's annual shareholders meeting will be held Saturday in Omaha, Neb., where tens of thousands of people show up each year to soak in Buffett's investment wisdom.