Yes but when you're a wealthy old tycoon without a mortgage...

Yes but when you're a wealthy old tycoon without a mortgage that's easy to say sob! You can afford to make the mistake if things go wrong (and they HAVE been known to - far too often for us to take it with a grain of salt)

That said, I'm guilty of holding just over 50% of my total assets in one stock in the o&g sector and it's paid-off so far...