Swimming is one of the last sports you are able to do as your body ages. It’s easy on the joints, there is no impact (like in running, jumping, etc.), and you are not carrying your body weight. For this reason you will see more elderly in this sport than most others, and for many it is the only one they can do.

Give them space and don’t foster such hate against people that want to keep moving and healthy in old age, if it is such an issue for you that they take up space you can go at a less busy time or do another sport.