If you are asking this question on a regular basis, maybe you're feeling a sense of loosing the reason you began whatever it is in the first place.
Sometimes, when the challenges get tough, that question can arise. It can be very worthwhile to try to answer the question because a person can loose track of why they are doing something if it goes into automatic without any seeable results of a beneficial nature.
This is the importance of love and deep desire, or a profound sense of duty to assist, provide for, change, prevent or perhaps serve a higher purpose beyond one's own likes and dislikes.
The point is the reason, purpose or goal. If I am eating something that weakens my health, what is the point of doing that? But if, for someone, life seems hopeless and the person is fed up with it all, they might say, "What is the point of staying on this diet, it's all hopeless anyway."
Sometimes a situation can occur when a person is sick of doing something that has lost its appeal or reason for having started it in the first place or simply that the action actually isn't needed anymore. To ask, "What is the point?" is useful in order to relook at our actions and perhaps reevaluate what we are doing so we will not waste any more time doing something that burns up a lot of energy and is either harmful or just not useful or needed. In any case, the point is to see if change is needed and, if so, to identify the need for that change. This moves things out of stuck and back into a directional momentum.