I hold BRK stocks and I expect it to underperform the market on average (but also be a very good hedge in case of big downturn). BRK is in big part short term treasuries then a stock portfolio then a core business (insurance, energy, rail, manufacturing etc.). While it's reasonable to expect the core business to outperform there is no way the whole thing is a favorite to do so because cash is a big drag.
Are you aware that BRK cratered during the 2009 stock market crash? During a crash, except gov't bonds, pretty much everything sells off equally. There is a joke on Wall Street after 2009: During a crash, correlation on all assets goes to one (1.0).