We could quibble about the meaning of "irrational", but I do agree that markets can be mistaken for longer than most people can financially back their conviction that it's mistaken.

In the case of Tesla vs Ford, there is probably a sense in which the longer the market is 'irrationally' convinced of the value of Tesla, the less irrational it actually is - it's a bet on Tesla's viability and vision, and the longer it seems like a good bet to most people, the more likely it is that it is a rational bet to have made.