Q: Am I Crazy to believe in the Greek Gods/Goddesses?
A: Belief is defined as:
1. something believed; an opinion or conviction.
2. confidence in the truth or existence of something not immediately susceptible to rigorous proof.
3. confidence; faith; trust.
4. a religious tenet or tenets; religious creed or faith.
So to answer your Question, No.
A person will believe many things during their lives that have not been proven as 100% fact.
Take the Theory of Evolution. The Reason it is called a Theory is because it has not been proven 100% scientifically to be a fact. However look at all the scientific fields based on it. All the scientists who work in those fields believe in it.
If i believe that I will wake up tomorrow, will I ? Well probably, but there is no proof that i will. I could die in my sleep.
What you choose to believe, is simply a matter of choice. You choose what to believe based on your own personal preference.
Is Pepsi better than Coke ?? 50% say yes.
Is Coke better that Pepsi ?? 50% say yes.
Take your pick.
Whatever you choose to believe is OK. In the end your the one who has to decide to stand behind your convictions what ever they might be.