Why laughing is necessary?

Hello!
Here I'm with my new post. So, let's get started.
First of all, we should know about the difference between smiling and laughing. These terms are basically use for same purpose. Express happiness in front of others loudly is known as laughing. Smile is soundless.
Stress makes our immune system, psychological and harmonal system weak. Laughter is one of the best stress relievers. It is also necessary because it relax our muscles for about 45 minutes.
It is good when we laugh normally in our routine.During speaking you can laugh if hilarious thing came. Our society think the person who laugh all the time have some sort of psychological issues. Some researches say excessive laughing may causes heart dilemma or may cause dead heart.

It is good but making it a source of income is not right. It is prevalent nowadays, laughing became a source of earning.
This is my opinion if your point of view is different then you have right to criticize me.
Thanks for allowing me to post in this community.
@mazhir.chisti