Reading about the 1920s stock market crash recently it struck me that many men ruined themselves because they were unaware that their previous success owed more to luck than to their mastery of the situation.
I think a public stock market is a hard game to "good" at - far more luck based than other things. I mean it's a pretty efficient market with really high incentives to get information, and hence pricing, reflected in your positions.
Whereas - a person opening a construction company just has to beat all the super-flakey contractors that already exist and of course sell like hell. This is far less luck than the stock market is.
