Complex sentence: He actively encouraged the public's perception of him as an unschooled peasant, while his ambition, his bold pronouncements to journalists, and his insistence on depicting his own life in his art gave him a reputation for unbridled vanity.
Split into simpler sentences: He actively encouraged the public's perception of him as an unschooled peasant. While his ambition, his bold pronouncements to journalists, and his insistence on depicting his own life in his art gave him a reputation for unbridled vanity.