During good seasons you produce extra to set something aside you can live off during lean years. You feel more secure and successful if you've accumulated some capital. You may even want to start your own business. Maybe you want to retire one day and live off your savings. So many people produce surpluses.
Some people produce large surpluses.
For example, because the sun shines, plants use energy from the sun and minerals from the soil to grow, and various human methods can be used to increase production, one farmer can effectively produce enough food to feed 100 people. At the one extreme, you hold someone up at gunpoint or you knock him unconscious or even kill him and take what you want from him. Less crude is to enter someone's home or farm at night or when they're absent and to surreptitiously take what you want. You can also use all kinds of trickery and deception to defraud your victims. This is what the con artist does.