This is a purely individual reason and let me assure you that it is the only point in this slider that is solely about Messi and not Argentina. Everything that Lionel Messi has today, he not only owes it to his brilliance but also a bit to Barcelona.
This is a club that showed immense faith in him despite the fact that he had just hit his teens. Since the age of 13, he has been plying his trade for the Catalans and has achieved everything there is to achieve at club level.
However, the hunger still persists and he could win a lot more with Barcelona as the years go by. If he cuts short his international career now, he can prolong his time with Barca by at least a couple of years – and he could consider doing that for a club that gave him the platform to reach greatness.