why do dreams sometimes fail?

Dreams sometimes fail because they are sometimes  impossible to reach. For instance I always wanted to be as tall as shaq, but know that i know my body , i know i will never be as tall as him. There are also times when your dreams are not reachable because of financial situations. This shown in the book when George and Lennie want to buy a ranch and if it wasn't for Candy they wouldn't have been able to reach their goal because they only have 10 dollars. This is also true when my best friend wanted a new car for his birthday and he didn't get one because they are too expensive for his parents to buy. Dreams also fail because of freak accidents. For example my parents were supposed to go to Las Vegas until 9/11 occurred and their trip got cancelled so there dream failed. Another way that a dream can fail is when a person a person is not determined to make it happen. For instance my Aunt had a dream that she would be thin again but she did not work at so she did not lose the weight that she wanted to. So even if you have a dream you should set it in the conditions that will make it possible for you to achieve.