There are many ways of showing gratitude for the help you have receive: Eg, saying, “Thank you”, “God bless you”, etc. When a person fails to show appreciation for the help he has received, it is termed ingratitude.
Ingratitude is like a foul smell; it put good people off, offends them, and withdraws their hands from extending help to you. Normally, ungrateful people kill their upportunities in that they ruin their chance of getting help from others whom they have offended with their ingratitude.
The saying is true that ingratitude is fatal to its authors.