On the contrary, that's exactly how he became a multi-billionaire. He invested in a lot of things, *most of which turned out to be stupid decisions*. But enough of those investments turned out great that it more than made up for the ones that turned out to be stupid decisions.
Just look at how many things he tried to start that ended up folding.
The key is that you have to make the initial investment even in the dumb things if you want to see something really game changing. Same reason why the Department of Defense invests in ESP and psychic nonsense. Because if it had turned out that ESP and psychic nonsense isn't actually nonsense, then they need to have an investment in it.