Are there any advantages to living a sedentary lifestyle?
If you are a normal person without any medical issues then leading a sedentary lifestyle will not be an advantage over an active lifestyle. Most people who have sedentary lifestyles will find putting on weight really fast and easy mainly due to the high calories consumed in foods and drinks like alcohol and supermarket juices and enegy drinks. 99 % of people totally underestimate calories consumed because they don't count drinks.
A sedentary lifestyle will not improve cardiovascular strength which will be a plus in later life, does not build muscle which reduces by 1% every year after age 35 so in reality if you are getting bigger as you age it's going to be all fat.