Why did Śrī vyāsadeva write Māhābhārata?

Friend,

VEDA VYAASA is a role in Mahabharatam

VedaVyasa was observing, before writing observed the surroundings and worried how the Dharma ,Artha, Kaama, and Mokshams are violated by majority and even kings used to be adharmic and kamukaas.

Learned people were silent for some reason.

maha Pativra , Raaja Kanya, Ayonija, Paandava Patni , Yaagnaseyni was dragged into KURU SABHA and tried to DISROBED in presence of the Pancha Pandavaas ( Ari veera Bhayankara Warriors), Bheeshma, Drona , etc and Dritarashtra the emperor.

This is PARAAKAASTA OF DHARMA GLAANI 9 Violation of all Dharmaas).

This made Vyasa Deva very much despondent.

So HE WRITE ( GANAPATHY OR GANESH WAS HIS SCRIBE) THE MAHABHARATAM with 107000.verses.The longest EPIC IN THE WORLD.

It is called PANCHAMA VEDAM.

If any body gets a doubt about veda vakyam meaning, or upanishad meaninf or Puraana meaning , then ELDERS SAID READ ''MAHA BHARATAM''It gives solution to all.

That is what i know, and understood please.

Besides its epic narrative of the Kurukshetra War and the fates of the Kauravas and the Pandavas, the Mahabharata contains much philosophical and devotional material, such as a discussion of the four "goals of life"

As per directive from the Lord Brahma.