I just thought about this today. Every time you are transacting with bitcoin, you will be told that you have to wait for bitcoin confirmation. This is common with bitcoin gambling sites. What I know is that bitcoin transactions are irreversible. Then why is it that you have to wait for the confirmation before initiating anything?
Even though the possibility of a double spend is very low, some small rest of risk always exists.
That's why we are told to wait for confirmation.If however you have 100% trust to your other party, because you know him for many years and everything always went smooth and fine you don't need to wait of course.