Stay within a well-defined circle of competence. - Charlie Munger

Obviously, you have to know accounting. It's the language of practical business life. It was a very useful thing to deliver to civilization. I've heard it came to civilization through Venice which of course was once the great commercial power in the Mediterranean. However, double-entry bookkeeping was a hell of an invention.
And it's not that hard to understand.
But you have to know enough about it to understand its limitations — because although accounting is the starting place, it's only a crude approximation. And it's not very hard to understand its limitations. For example, everyone can see that you have to more or less just guess at the useful life of a jet airplane or anything like that. Just because you express the depreciation rate in neat numbers doesn't make it anything you really know.

All I want to know is where I'm going to die so I'll never go there.

The big money is not in the buying and selling ... but in the waiting.