Like WEBspired, we're in our mid 50s with BrkA and BrkB comprising more than 80% of family net worth. We began buying in March 2000 and added to the position consistently. We realized the portfolio carried concentration risk but felt the % of cash to mkt cap enabled patience and opportunism when dealing with herd behavior in the market.

The fundamental buying decisions were built on the mix of earning streams from reliable & diverse businesses.
Our understanding of Brk earnings and business strengths/weaknesses has lots of sources, but was in no small measure informed by several of the posters here - the cast of characters familiar to nearly everyone. Those of you getting lots of recommends over the years have very likely helped put lots of kids through school and secured retirements for fellow shrewdites. Again, MY thanks to all the usual suspects.

We've selectively added 600 B shares for retirement accounts in about 10 increments in the last 18 months with a aggregate basis of $297/share. We've tried to act when P/B seemed favorable. Perhaps with some measure of fortune, this was drawn from a 401K equity fund position that went to a GIC at 3% in December 2021. We also used a portion to build 18-24 months of expense time (short term treasuries & money mkt) to allow any corrections to mean revert - again some portfolio concentration insurance of sorts.

We've been thinking about lowering our Brk exposure for years now. This would only be done in the retirement accounts. The index candidates are the obvious target for us, but the relative valuation has not presented the moment for us. We likely would consider doing some of this when we felt we could get risk adjusted earnings parity for our Brk positions. We'll begin drawing down in the next couple years.