Why do you think Jesus did not write his own gospel?

The first writings about Christ's life weren't recorded until over 150 years after His death. What is difficult for us to understand is in those days, very few people could read. Everything was oral and practically nothing was ever written down.

His ego didn't think he needed to, so he left it to his 4 slaves, who each had to paraphrase each other as they were threatened with crucifiction.

Why? He was busy preaching, as were his Apostles.

See http://www.newadvent.org/cathen/06655b.htm

"All recent critics admit that the contents of our four Gospels are intimately connected with more primitive accounts of Christ's life, which may be described, in a general way, as an Oral Gospel. They are well aware that Jesus Himself did not consign to writing His own teachings, and directed His Apostles not to write, but to preach, the Gospel to their fellow-men. They regard as an undoubted fact that these first disciples of the Master, faithful to the mission which He had entrusted to them, began, from the day of Pentecost on, boldly to declare by word of mouth what they had seen and heard (cf. Acts 4:2), considering as a special duty of theirs "the ministry of the word" (Acts 6:4). It is plain, too, that those whom the Apostles immediately selected to help them in the discharge of this most important mission had to be, like the Apostles themselves, able to bear witness to the life and teachings of Christ (cf. Acts 1:21 sq.). The substance of the Evangelical narratives would thus be repeated viva voce by the early teachers of Christianity, before any one of them bethought himself to set it down in writing."

(And, no. I'm not Catholic. This just made sense.)

The gospels were all written after he was crucified. There really was no need for the books when he was alive, or in the very early church times. He was too busy with his ministry and probably just wanted his disciples to do that.

He did it is rumored to be noted on the Vatican library catalog but you'll only read it if you become a very high ranking member of that organization. +2

Jesus obviously didn't 'live to tell the tale',
disproving his 'resurrection';
or
he was so carelessly, negligently in a hurry
to 'do a runner' & return to Daddy's home,
proving (1) he did not care for the mankind as claimed,
and/or (2) the Romans had scared the shit out of him!
*
Very dishonorable of Jesus, whichever way you look at it.
This is why/how:
The Birth of the ‘Christianity’ brand after pious Jesus was crucified.

…And the 11 so-called ‘disciples’ of Jesus (Judas was the fall-guy, scapegoat) sat huddled in a small room and contemplated: “Oh sugar! How do we clean up this mess and redeem ourselves? People have seen us with Jesus, seen us denying and betraying him as well, they will stone us to death!”! – (as per the tradition of that time)

Peter said (and Paul-John seconded) to the group: ‘Lets hide/destroy Jesus’s body and start a new business, creed in the name of Jesus –the dead Jew. John sprinkled some water on Jesus as a ritual (Baptised) which everyone saw. Lets sprinkle –‘holy water’-- on our consumer-group as loyalty-scheme!’

‘But who would believe us? We have no service to offer, no product to sell!
We will tell everybody we saw him rise & go to skies/heaven. There would be no body for evidence! Then we will offer those who vouch to follow us: God’s promise of ‘life after death’! Everybody is afraid of death & nobody will return to ‘call our bluff’!

How would we entice & recruit consumers before making them loyal?!’
‘That’s easy! Just make them ‘consumers-by-birthright’ by (1) labelling all natural life-processes from womb-to-tomb, especially sex & conception as the ‘original sin’, so everybody automatically becomes a sinner-by-birth and has to seek redemption and (2) keeping customers ignorant of truth by calling ‘ignorance is bliss’ & ‘seeking of knowledge’ as a sinful temptation, a taboo, a bigger sin, such that eating the fruit of [carnal] knowledge of good & evil drove Adam & Eve out of paradise [where thery could live in ignorance forever… just like ‘heathen’ animals]…!

‘Then all of us and our club of generations of clergy would be ‘set up’ for a cozy life, eternally! Free solid-stone, high-ceiling housing, free food that too ‘best-cut’, we shall never need to work again, just ‘gob the gospel’! --- plus those sick child-molesters among us would have continuous supply of young boys to bugger as a ‘bonus bounty’ from our Lord, Jesus’s father-God, Amen!’

Thus was born the first business with brand-name ‘Christianity’ – the fore-runner of Coca Cola, Microsoft, Virgin and F C U K, with a board of 11 directors and it remained by far the most profitable ‘service’ industry by late 20th century AD, establishing monopoly by deceit and subterfuge, circular-illogical-irrational arguments of ‘divine authority’, selling an abstract, intangible faith-‘product’: “promise of immortality in afterlife”, a product with long, almost ‘eternal’ shelf-life, --but absolutely no value, no credibility, “no money-back, no guarantee”, no effect & no utility-in-futility.