There's a belief in financial markets that once taxi drivers start asking you about particular investments, it’s the top of the market. Many are very smart, but they’re unlikely to be investment experts.

Sam Stubbs has experienced this twice. Firstly, when New York taxi driver asked about internet companies in 2000, a few months before the internet bubble burst. Secondly when an Auckland Uber driver asked him which cryptocurrency to buy.

After observing the cryptocurrency market, without ever investing a dollar in it, Sam's conclusion is that it’s a great place to gamble, but a terrible place to invest. 

In this article on Stuff, he explains why.