Investors who were patiently waiting for a stock pullback are finally giving up and are buying anyway, closely followed trader Art Cashin told CNBC on Wednesday.

U.S. stocks were higher Wednesday after strong-than-expected quarterly earnings reports before the bell. The and have both risen in 12 of the past 15 sessions, and the Dow and S&P 500 remain on pace for their best January since 1989.

The stock market rally isn't driven by news but investors "late to the party beginning to say, 'wait a minute, this train is pulling out. I can't wait much longer,'" said Cashin, UBS director of floor operations at the New York Stock Exchange.

He added that perhaps a lower U.S. dollar "to some degree" was helping fuel the rally Wednesday. The greenback was sliding to three-year lows against a basket of major currencies.

"Everybody's been waiting to buy the dip," Cashin said in an interview on "Squawk on the Street." Now investors are saying, "'I may not get that dip,'" Cashin contended.

He also said "we may be seeing near-spontaneous combustion from Mr. Dalio's rally."

On Tuesday, Bridgewater Associates founder Ray Dalio predicted investors will see "a market blowoff" rally, fueled by cash from banks, corporations and investors. "If you're holding cash, you're going to feel pretty stupid," the hedge fund manager said.

"[Dalio] talked about ... people who haven't gotten in yet and I think you're seeing a little bit of that here," Cashin said. "It wouldn't take much to turn these sparks into a real blaze."

Later on "Squawk Alley," strategist Jim Paulsen said he wouldn't disagree with Cashin's assessment.

"It's an incredible market. It's got incredible price momentum," said Paulsen, chief investment strategist at Leuthold Group. Wall Street may see a brief pullback, but the market's run higher is "impressive," he said.