It's not *all* a fraud.
Enron was a hugely successful energy and other services business with billions in assets. And fraud on top.
Madoff was a highly successful founding member of Nasdaq/inventor of computer algorithmic trading/had a successful fund. With a giant Ponzi festering on the side.
Crazy Eddie was a highly successful mobile phone selling store chain with a national presence. With fraud on top.
Worldcom had $100 billion in assets and a large thriving business. With fraud on top
Theranos was a legitimate testing services business doing good volume with major pharmacy chains. With a core claim - pinprick blood testing - that was a fraud.
It's pretty simple: Legit businesses that are unimpressive, need lots of capital, can't make ends meets legitimately (like, say, a massively money losing electric car business that needs $25K net loss per car to make the product sexy/sporty enough to be noticable in the market), has an aggressive founder who views it as a game, etc, often go to fraud out of pure necessity.
It's not either/or. Musk can be both ballsy entrepreneur who pushes risk and had some big wins AND be a giant fraud on his FSD claims or 2017 Model 3 production or battery swap claims or Solarcity acquisition or any number of other things. In fact, being a successful entrepreneur and being a fraud tend to go hand in hand if you're in shady government subsidy "green" businesses. Add in a "world saving" narrative and the odds are even higher. Have you ever seen the financials of most environmental charities?