I think Keith Johnson's lawsuit against Elon Musk, legal record, from the articles I read the points I got stated.
“Defendants falsely and deceptively claim that Dogecoin is a legitimate investment when it has no value at all,” Johnson said in his complaint, filed Thursday in federal court in Manhattan.
It can be concluded that Elon Musk only said Doge was an investment, Elon Musk did not deceive Keith in this case, he should have known the investment risks, why Keith trusted Elon, it seems like a case of legal defects.