Having all of your resources in one place; putting your money or hopes or future into one thing.
'Eggs' are delicate, and 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.
1) You don't want to keep all of your eggs in one basket. You might lose everything!
2) Tom had all of his eggs in one basket -- Yoyodyne.com stock -- and when the stock market crashed he was bankrupt.