The higher in price a quality asset goes, assuming fundamentals remain constant, the worse a buy it becomes. i.e. HYPE was a brilliant buy at 10, fantastic at 20, great at 30, good at 40, decent at 50 and so on.. There will come a point where it becomes a "bad" buy, despite being a good asset. And the same in reverse. There are some absolute trash, scam, vapourware projects which, at the right price, represent brilliant buys.