Surabhi, I agree with you! I always wondered why Duryodhan, even after winning Indraprastha and exiling the Pandavas for 13 years, was still not satisfied. He hated that people still supported them. He wanted both the kingdom and the support/love of his praja, but the people of Indraprastha were very pro-Pandavas and the people of Hastinapur were divided after seeing his treatment of Draupadi in the dice game, so he still wasn't satisfied.
If being a King was truly what Duryodhan wanted, he'd have worked hard for 13 years to develop Hastinapur and earn a good name for himself, but instead he spent it chasing the Pandavas, trying to attack them, getting humiliated in turn, and in the end, he never truly became King because he got killed in the war for his green and sins.
Yudhisthira was given a barren land for his kingdom, Khandavaprastha, and with his brothers' help he developed it and created a beautiful flourishing kingdom. Duryodhan was given an already flourishing kingdom but even with the help of 99 brothers did nothing to progress it.
That in itself proves the merit of both as King.