I think by "actually not a great investor in the way people think", what you're saying is that he isn't a particularly outstanding stock picker. To the extent that that's the way in which people think he's a great investor, it's because lots of (most?) people think investing is just stock picking. But what makes him a great investor is exactly what you outlined. He found a great strategy - insurance float for leverage - and has executed it well for decades.
It seems weird to me to say, "he's not a great investor, he just found a great investment strategy and executed it really well!" What makes someone a great investor if not that?
It seems weird to me to say, "he's not a great investor, he just found a great investment strategy and executed it really well!" What makes someone a great investor if not that?