The problem with your logic is that when Berkshire takes a position in a new company, you, not being a BRK shareholder, must pay a significant premium to clone

The problem with your logic is that when Berkshire takes a position in a new company, you, not being a BRK shareholder, must pay a significant premium to clone that position. In other words, once it becomes public info that BRK bought a lot of company X stock, that stock will likely have jumped 10-20%, and you're forced to pay the higher price to maintain parity.