The IPO of crypto exchange Coinbase on Wednesday has captivated fans of digital currency and investors as they speculate on the potential for a $100 billion valuation on the company.

Just don't count New Constructs CEO David Trainer among the wild-eyed Coinbase bulls.

"I think it's [Coinbase] worth closer to $5 billion or $10 billion as opposed to $100 billion," Trainer tells Yahoo Finance Live. "Look, this is the brokerage industry — it's not new. Coinbase is not reinventing the wheel here in any way. They are just trading a new product. There is no reason that the New York Stock Exchange or Nasdaq couldn't also potentially trade crypto."

Trainer points out several red flags on Coinbase, including the inevitable new competitors likely looking to get in on the crypto action (see investment banks) and the potential for current rivals to cut transaction fees to zero.

Corporate governance is also a worry of Trainer. He points out that given the company's dual class structure, co-founder and CEO Brian Armstrong will hold 22% of the voting power. Meanwhile, all Coinbase executives and directors collectively hold 54% of the voting power.

Trainer thinks all of these factors set Coinbase up to let down investors who are expecting eye-popping growth over the next five years.

Says Trainer, "We think everybody that can trade crypto will want to get in and get a piece and you will see a race to the bottom in terms of margins like what we have seen in stock grading, which is zero commission. So the idea that Coinbase would grow revenues 150% — to the combined revenues of Intercontinental Exchange and Nasdaq — while also having margins that are 40 to 50 times higher, we just think that means it's [the company] is expensive. Not to say it's a bad product or a bad company, it's just a little expensive right now."

At the moment, concerns about Coinbase's valuation are taking a backseat to the typical hype that surrounds a buzzy IPO on listing day.

Shares of Coinbase were indicated to open at $365 per share around noon Wednesday in the stock's public debut on the Nasdaq, according to Bloomberg. The reference price for the stock was set at $250 per share on Tuesday. Some experts have speculated the stock could approach the $600 price target released by MoffettNathanson on its first day of trading.

The optimism on Coinbase comes as bitcoin prices have surged to a record of more than $64,000. Meanwhile, companies from PayPal to Square to Tesla have sought to get more involved in the crypto space by purchasing bitcoin.