The long version

Nobody buys an E60 M5 by accident anymore — the rod-bearing maintenance schedule and SMG gearbox quirks are common enough knowledge in the used market that showing up as a buyer means accepting the deal already: cheap purchase price, expensive vigilance. That filter keeps the ownership pool small and informed, and the survivors tend to be owners who budget for the V10 the way a boat owner budgets for a marina slip. It dropped hard enough from new-car money to earn its badge here, and anyone still driving one is doing it because they specifically wanted this engine, not because it was convenient.