Is it justifiable to build a basketball court because there are basketball fans than to build a hospital because there are fewer sick people?

If these are the only criteria, then yes.

Basketball fans have expressed an increased need.

On the other hand, medical use is on the decline. Assuming that medical needs had already been met at level not requiring a new hospital there is no additional need for a hospital if medical needs are decreasing.

The problem is that we have to assume that nominal needs were being met before this argument was made. If needs were unbalanced prior to this everything changes, but we haven’t been supplied this information.

Now if we go the other direction.

Is a basketball court a need? No. Therefore, has it actually negatively affected the basketball fans by not building the court. No, as it is more of a want than a need as described.

Should a hospital be built when there are fewer sick people? Hospitals are massive complexes requiring many many support businesses and personnel to operate at a massive expense. We have no knowledge if another hospital is near by, if the medical needs of the area are already being satisfied, or if a new hospital would attract economic resources from the greater community to support it.

Without knowledge of the surrounding area all we are left with is the statement that less people are getting sick. So, resources would be spent on a problem that already seems to be resolving. Even if you make the argument that by having more resources available you would be able to further push the rate of sick people down further; this assumes that there are people looking for medical aid and not receiving it. Again, this requires assumptions that are not supplied, and have no guarantee that they exist in this community.

So, at the end of the day. Build the basketball court.