put all your eggs into one basket
put all (one's) eggs in one basket
To invest, devote, or commit all of one's energy or resources into a single venture, opportunity, or goal, generally at the risk of losing everything in the event that that thing fails or does not come to fruition. She has all her eggs in one basket with this merger deal. If it doesn't work out, I doubt her company can survive. I applied to several colleges so I wasn't putting all my eggs in one basket.