Most people's attitude towards life is diminishing marginal utility. But a few people may have increasing marginal utility. Or a pure attitude towards life (for example, a perfectionist is a bit like me, and the final profit is very useful to him), or an attitude towards a particular commodity.

People who increase the marginal utility of all commodities or specific commodities will get more satisfaction from the extra unit income than the previous unit income. Risk theory defines such people as risk lovers.

Risk means that there is a certain probability of losing the goods that can be determined originally, and there is also a certain probability of gaining more goods. At this time, the attitudes of people with increasing marginal utility and those with decreasing marginal utility determine whether they take the risk.

People with increasing marginal utility usually tend to take risks when they encounter risks. Because the utility that the risk may increase is greater than the utility that may be lost.

After considering the mathematical expectation, there is a criterion for judgment. It is the risk averse who decides that the utility is greater than the expected utility. It is the risk lover who determines that the utility is less than the expected utility.