Buffett is 91 and has underperformed the S&P 500 for the last decade. How confident are you in his future performance and that of his successors?
Berkshire is not a registered investment company like an ETF or mutual fund, so it pays taxes at the corporate level, including on the sale of appreciated shares of stock. A value ETF will periodically refresh its holdings and shareholders avoid paying taxes due to in-kind redemptions. There has been attempts to remove this break: https://www.cnbc.com/2021/09/29/senate-bill-that-would-end-e... .
I would put more money in ETFs such as VTI and VXUS than in BRK, but I think BRK is a reasonable place to put some money.
