Michelangelo neglected his own interests by not going to Rome, where his enemies kept pouring calumnies into the Pope's ears.
The Marquis of Carrara, as reported by Lionardo, wrote to Leo that "he had sought to do you honour, and had done so to his best ability.

It was your fault if he had not done more--the fault of your sordidness, your quarrelsomeness, your eccentric conduct." When, then, a dispute arose between the Cardinal and the sculptor about the marbles, Leo may have felt that it was time to break off from an artist so impetuous and irritable.

Still, whatever faults of temper Michelangelo may have had, and however difficult he was to deal with, nothing can excuse the Medici for their wanton waste of his physical and mental energies at the height of their development.
On the 6th of April 1520 Raffaello died, worn out with labour and with love, in the flower of his wonderful young manhood.

It would be rash to assert that he had already given the world the best he had to offer, because nothing is so incalculable as the evolution of genius.
Still we perceive now that his latest manner, both as regards style and feeling, and also as regards the method of execution by assistants, shows him to have been upon the verge of intellectual decline.

While deploring Michelangelo's impracticability--that solitary, self-reliant, and exacting temperament which made him reject collaboration, and which doomed so much of his best work to incompleteness--we must remember that to the very end of his long life he produced nothing (except perhaps in architecture) which does not bear the seal and superscription of his fervent self.