Unless your friend is a part-timer or making minimum wage, spending 6 months salary on a bike is outrageous, at least to most people, myself included. But you're asking the question in a forum where opinions where bikes are concerned are extremely skewed.

Unless you are making in excess of 6-figures, have no debts, are independently wealthy, or have no dependents spending that much money on a bike is completely irresponsible.

So, yeah, if your friends is none of the above then he's stupid. Just MO.