In addition to Kardashian, Mayweather and former Boston Celtics star Paul Pierce, the defendants in the case included Steve Gentile and Giovanni Perone, the co-founders of EthereumMax, and Justin French, a consultant and developer for the cryptocurrency.
The judge’s ruling said: “This action demonstrates that just about anyone with the technical skills and/or connections can mint a new currency and create their own digital market overnight.
“Likewise, the action emphasises the power of social media in allowing celebrities to directly communicate with their millions of fans with a touch of a button.
“These two facts, together, have seemingly allowed unvetted and highly volatile investment ventures to go viral based solely on the paid-for word of celebrity promoters.
“Losses have inevitably followed. The court acknowledges that this action raises legitimate concerns over celebrities’ ability to readily persuade millions of undiscerning followers to buy snake oil with unprecedented ease and reach.
“But, while the law certainly places limits on those advertisers, it also expects investors to act reasonably before basing their bets on the zeitgeist of the moment.”
Michael Rhodes, a lawyer for Kardashian, told NBC: “We’re pleased with the court’s well-reasoned decision on the case.”
The investors can refile the lawsuit if they amend some of their claims by 22 December.
It comes two months after Kardashian agreed to pay $1.26m (£1m) and not to promote cryptocurrency for three years to settle claims by the US Securities and Exchange Commission for her failure to disclose the $250,000 payment she received.