Ok. Let’s use a 40 year time horizon (I don’t). Their stock price compounded at better than 19% per year (US$, dividends included). And for the first 25 years of this time period they had some pretty crappy insurance businesses. Their stellar results were driven primarily by their investment decisions - which you characterize as ‘mediocre.’
Please square that circle…
PS: Fairfax is a contradiction. What people think about the company. And what the company actually did. There is, IMHO, a massive disconnect.