“Putting all your eggs in one basket” is a well-known metaphor for a situation where someone is depending completely on just one idea, plan, or person, to the extent that they have no other option if things go wrong. There is no “Plan B”. It is usually used to describe someone who is being overly confident with a singular path and engaging in unnecessarily risky behaviour. The inference being, that if all of your eggs were in one container, and that container was damaged, you might lose all of your eggs in one quick and painful moment.