Three Lamborghinis parked Monday morning near a major cryptocurrency conference in New York did not belong to investors in bitcoin, or any other digital coin.

Instead, two of the luxury cars were from Broadway Supercars, a New Jersey-based car rental, and one belonged to company founder John Nouri.

He said he was hired to park the cars for about five hours Monday morning on Sixth Ave just outside a Hilton hotel, where more than 8,500 people are expected to attend CoinDesk's Consensus conference that kicked off Monday. It's part of a promotion for the conference, and cryptocurrency exchange BitMex, he said.

"We do a lot of this for a lot of companies all the time," Nouri said. "It's an attention grabber. It's for the people walking in. They all say once you make money in crypto, you buy a lambo."

"I never made money with crypto but I have ten lambos," Nouri said. His company rents Lamborghinis out for $1,000 a day.

Bitcoin multiplied 13 times in price last year, minting cryptocurrency millionaires. A Lamborghini can cost about $200,000 or more, and the luxury cars have become an internet symbol for volatile cryptocurrencies' massive potential for wealth creation.

"I see a parallel between young people that are really willing to become very rich with the very high-risk investment, and … the fact that our customers are very young," Lamborghini CEO Stefano Domenicali told CNBC in a recent interview.

Case in point, coder Peter Saddington, 35, bought a Lamborghini three years ago for $200,000 with 45 bitcoins. He'd spent less than $115 on the coins when cryptocurrencies were at the very fringes of mainstream interest.

Bitcoin traded near $8,700 early Monday afternoon, less than half their worth in mid-December.

— CNBC's Robert Frank and Ali Montag contributed to this report.