I think he keeps the share extremely high to discourage short-term, quick return investors
He doesn't keep the price high, market demand keeps it high. Warren refuses to do 'stock splits'....which bucks the norm of most company's. As a result the price of B/H continues to slowly creep up. I can remember in the early '80's it was trading around $8,000.
"It's not the size of the dog in the fight, but the size of the fight in the dog"