He became King.

«They love freedom, my queen,— he said, taking her hand tenderly. "Not gold, not honors, but heaven. A dragon chooses its rider, not the other way around. It senses shelter. He senses betrayal from afar, and its punishment will be instantaneous. — He spoke of the dragons' favorite food - sheep, goats, bulls, and sometimes reindeer, if they could be obtained. But their greatest delicacy was always their enemies, whom they trampled with their huge paws, burning each one with hellish fire, as soon as they heard the command "Dracarys" - burn them all.»

It was so like Viserys himself, he had no patience for traitors, burning them one by one, enjoying the pleas of those who had once called him the Beggar King, who had mocked him and his Great House. Dragon blood did not tolerate such things. He had grown accustomed to the Throne at once, cold, even though it had once been fused by the fire of the great dragon Balerion, on which his ancestor, Aegon I, had sat, and in some places there were small scars from the swords that made up the entire throne, but that was less important than the fact that he had sat on it. The scarlet and black fabrics of his robes, thick and heavy, cascaded down like frozen blood and shadows. There was a hint of madness in his voice when he spoke of dragons, something his wife had heard about his father. She had seen how years of rule had changed him. There were deep lines about his eyes, a hard line about his mouth. She looked at him with concern, but he never noticed it—or did he want to? With each passing day, Viserys looked more like his father, the Mad King. The same manic passion in his eyes, the same instability of mood. His silver hair, reflecting the firelight, was streaked with gray, as if the burden of the throne had aged him at once.

He got what he wanted—the Throne, but he is losing what he valued—his sanity.