Do I think Berkshire is the better company? Absolutely. But there's a case to be made that Markel is the better investment, starting at current valuations (MKL 1.14x BV, BRK ~1.45x BV).

Markel BV per share is around $1530. Compound at 10% for 10 years = $3970. Apply a 1.45x multiple to BV anywhere near the end of that period (not unrealistic, as it was aroudn that level as recently as Jan 2025), and per share price is something like $5750, a respectable 335% return.

Berkshire -- take $350 BV/ B share, grow at 10% for 10 years, apply a (higher) 1.6x multiple, and you get a B share around $1450, 290% return.

Under these assumptions, you are right that MKL is a potentially a better investment.

However there could very well be rough seas ahead and no one can take advantage of disruption in the overall economic conditions and/or markets better than BRK. And second, I think BRK's insurane business is far better than MKL's. And third, BRK is beter at buying whole businesses than MKL. So I would not be surprised if BRK outperforms MKL over the next decade.

Finally even under your assumptions, the margin isn't big enough (IMO) to warrant a significant allocation to a worse opportunity in terms of quality. IOW I need a higher relative return from MKL to justify allocation to it because I am giving up on quality & stability just like you would demand a higher return from junk bonds than US govt bonds.