There doesn't need to be a point. There are some obvious benefits of physical activity for those that are motivated to do it. For others, the benefits are not motivating enough to do it and may choose to spend their time doing something else.
I am an ectomorph (thin with high metabolism) so I was skinny growing up, and weaker when it came to playing sports. Strength training changed the game for me and allowed me to compete without that strength disadvantage. Over time, it became very enjoyable, increases my appetite, allows me to sleep better, releases more endorphins and a calmer state of mind.
I think it becomes a long-term lifestyle when people enjoy it, and maybe a short-term activity to maybe lose some weight or get in shape for a particular event if it's not enjoyable.
If you don't train, just think of what it would be like to be maybe twice as strong or faster or more agile. It's a great feeling.