While Oscar is certainly a big event and a prestigious award to win, it's not the only thing out there. Golden Globe is one that immediately comes to mind, and there are others. Sometimes I think that winning or not winning an Oscar is not of such tremendous importance as people make it to be.
The Oscars are not the only criteria for choosing the best films as beauty is in the eye of the beholder. One film that wins The Oscars might be considered the best film to one person, and the worst to another. This is why criteria for choosing the best films can be based upon many different things.