Buy when everybody is pessimistic.
We might not be there yet but it's close.
How can we be close to pessimistic? Bitcoin was $100 a year ago. True despair-pessimism is a long WAY DOWN.
There are lot of people who entered the game way above those 100$, they are certainly close to pessimistic stage, some of them are in it for some time. The others won't let it go that low, no chance.