I believe the answer to your question would be when the big supermarkets accept some form of btc for their goods.
Many gigantic industries seen Bitcoin as a joke, I think many people become comfortable when the bitcoin prize boost. And also when the bitcoin accepts such as a paying transaction across over the world.Imagine when you buy a stuff in a store and you forgot to bring your cash, with the help of bitcoin (problem solved!) And lastly we need to give people prior knowledge in terms of how powerful bitcoin is it to become it more popular so that many people use bitcoin.