>The incentive is that you could potentially enjoy something briefly and that's the best deal you can get.
Many people might say that is a lower incentive than to being able to leave your family better off than they were, or in your more greedy interpretation, so that their children and their children can enjoy something less briefly than you were able to.
Many more people are single and don't plan on having a family. And for those who have .. tax is always lower than 100%. You won't leave your family worse off by earning more money, regardless of the specific level of the tax.
Many people might say that is a lower incentive than to being able to leave your family better off than they were, or in your more greedy interpretation, so that their children and their children can enjoy something less briefly than you were able to.