There may not be any specific reason for a startup failure. It is quite normal that only a small percentage of startups find a unique spot on the 'fitness landscape' that would allow them to grow and prosper. The rest may be just as well equipped and funded as the lucky ones, but still they will perish. Randomness among reasons for success dwarfs most of other factors.

The rational strategy is not to try to discover some 'success recipe' (there is none), but to do a lot of tinkering, be prepared for many false starts, and make sure that the unavoidable failures will not kill you as an entrepreneur.