Locutus
King of the Collective
Actually, I think the person you're describing is Kublai Khan, he moved the Mongol capital from Karakorum to Dadu (now Beijiing). Although this was a bad move and caused the various Mongol khanates to grow further apart, it was in itself not something that made the Mongol empire collapse (although it did contribute to the collapse, which occured 70 years after Kublai's death). Kublai is generally seen as the second greatest Mongol ruler who ever lived (after Genghis of course) and although the economic policies of him and (especially) the rest of the Yuan Dynasty did do China much harm in the long run, he certainly wasn't a bad ruler who spent all his money on entertainment. Some of his accomplishments include: defeating the Sung dynasty, rebuilding the Grand Canal, repairing public granaries, extending highways, promoting the creation of trade routes throughout the Eurasian continent (e.g. by reinstating the Silk Route), building magnificent palaces in Dadu and Shangdu, fostering Chinese scholarship and arts.
Ligdan Khan ruled much later, in the early 17th century, and was the last of the great Khans. He is generally also seen as a capable leader. He united many Mongol tribes to defend their homeland (roughly present-day Mongolia plus Inner Mongolia) against the rising power of the Manchu; he put up a good fight and only after Ligdan's death were the Mongols subdued by the Manchu.
Ligdan Khan ruled much later, in the early 17th century, and was the last of the great Khans. He is generally also seen as a capable leader. He united many Mongol tribes to defend their homeland (roughly present-day Mongolia plus Inner Mongolia) against the rising power of the Manchu; he put up a good fight and only after Ligdan's death were the Mongols subdued by the Manchu.