Hey, that's what makes a market. We all agree that many things might happen; it's really a question of what the probability curve looks like. At the time of writing, my SWAG is a 75% chance that Markel outperforms BRK on price, mainly though the multiple to book reverting to its historical mean. It can do that without the results for both businesses being much different than they've been historically. A 75% chance of 45% outperformance should be worth something like 33% to me, all else being equal. For you, that margin isn't big enough (and you distrust the inputs); for me, it justifies allocating some capital to MKL rather than BRK.

Importantly, this isn't a one-time bet <<mesdames, messieurs, les jeux sont faits>>. It's more like a Bayesian prior. If MKL's combined ratio goes through the roof, or it looks like they're persistently under-reserving, or Steve G starts investing the portfolio in SpaceCoin, I'm free to change my mind and reallocate from MKL back to BRK (or to Chubb, or Kinsale, or Fairfax, or...). Conversely, if the gap in projected outperformance widens further, or Markel looks to be getting better at dodging the rakes, I might even sell some BRK (shame, shame).

Math is just a tool to think with, but (unpopular opinion) I've never been one to trust my gut. My small intestine is good at extracting nourishment, but bad at making rational capital allocation decisions.