Why make du'a ?

بِسْمِ اللهِ الرَّحْمنِ الرَّحِيمِ

Dua is defined as any invocation or prayer addressed to Allah (SWT). In our times, we find many reasons why people do not make Dua; we forget, don’t know how, or just do not think it will be answered. Fundamental to this is the loss of dependence and trust upon Allah. As Muslims there is something very wrong when we believe our Duas won’t be answered.We do not turn to Allah in our times of need and instead put our trust, dependence and hopes on worldly things that we think will help us. Although these temporal things are the means through which our Duas can be answered, the root of our being should be trained automatically to turn to Allah and not anything or anyone else. Through Dua, we strengthen our Imaan and our relationship with Allah, as well as heighten our awareness of cause and effect that can help inspire and motivate us to be closer to Islam in our lives.
We find many reassurances throughout the Quran for those who make Dua. Allah the Exalted, has said: “And your Lord says: Pray unto me: and I will hear your prayer” (Quran 40:60), “Call upon your Lord Humbly and in secret” (Quran 7:55), “When My servants question thee concerning Me, I am indeed close (to them): I listen to the prayer of every suppliant when he calleth on Me” (Quran 2:186), “Is not He (best) who listens to the (soul) distressed when it calls on Him, and who relieves its suffering.” (Quran 27:62)
Aisha radhiallaahu anha said, “No believer makes Dua and it is wasted. Either it is granted here in this world or deposited for him in the Hereafter as long as he does not get frustrated.”
In fact, it is even wrong to never make Dua, “Whosoever does not supplicate to Allah, He will be angry with Him.”[Saheeh Jaami`as-Sagheer #2414]
We can and should make Dua in every condition, i.e. in hardship and in prosperity.