can someone give the reason why the stock market become volatile?

Because there is so much uncertainty ... wars, elections, bad weather

Yes, fear, greed and uncertainty. IF economic indicators (such as jobless numbers, or retail sales etc..)or earnings announcements become uncertain, volatility tends to increase.

Obviously NOPE.
1000s of REAL and unreal things cause market to change.
"volatile" is a vague term depending where u stand