[put all one's eggs in one basket] {v. phr.}
To place all your efforts, interests, or hopes in a single person or thing.
* /Going steady in high school is putting all your eggs in one basket too soon./* /To buy stock in a single company is to put all your eggs in one basket./* /He has decided to specialize in lathe work, although he knows it is risky to put all his eggs in one basket./