You don't need a famine to starve to death when you're a subsistence farmer, you just need your local area to suffer an unexpected weather event. Too much winter, too much heat, too much rain, too many storms, too many insects. Take your pick of natural disaster. When you and your entire country are subsistence farmers, there's not exactly a lot of surplus or distribution networks to get you replacement food when your local area suffers.

This is pretty uniformly attributed to government policy, not "Capitalism". - https://en.wikipedia.org/wiki/Great_Famine_(Ireland)