What is the point of being grumpy?

An ailing father is mad at his son because he could not join him for Thanksgiving.
An employee is grumpy with his co-founder for working extra hours.
An investor is unhappy with his portfolio for missing the quarter MAU.
A customer is grumpy for poor vendor because he is not giving timelines of the project delivery.

Why don’t we humans be little rational? Don’t we know our time in this life is limited? We have to live in harmony, peace.

Every problem has a solution. But being grumpy, mad or egomaniac will make things even worst.

Why are we letting our insecurity and weakness effect environment around us?

“We suffer more often in imagination than in reality”
― Lucius Annaeus Seneca