There are a number of distinct reasons that people adhere to low carb diets.

Professional

This is my reason for trying these kinds of diets. As software engineers, we spend a large proportion of our time living sedentary lifestyles. We sit in the office or at home and zone in to our work for hours on end. This can be quite destructive to your health over time no doubt. Since we are not moving around so much, we are not burning energy so much and so the effects of carbohydrate rich diets are much more pronounced!

Medical

You may have been prescribed Keto if you have epilepsy or for a number of different conditions.

Experimentation

Just for fun.

Cosmetic

You want to lose weight.