@TNT261 Well the cliche works because that is how it was in real life sometimes. I mean look at how bad the succession crises got in some of these countries. I mean there some points in Chinese history that the feuding in the royal family was even worse than game of thrones. Though I do believe there were people who rejected the right to suction.
As for why they would fight over it, the biggest reason is usually just greed and narcissism. But there is also other reasons like
1. The one who wins the crown assassinating his/her family members afterwards to eliminate threats before they could move against them. SO you wanted to be the one crowned just to survive.
2. Actually wanting to use the crown to change the way the country is now.
3. the nobles under the royal family pushing you into the fight so that they could benefit from your ascension to the thrown.
4. Also forgot sometime the parents (especially when there are multiple wives/concubines) where the parents groom you to be interested in winning the throne. I mean look at Alexander the great who had his mom constantly telling him since he was a toddler that he was the son of Zeus, king of the gods.
Now saying this, I will admit that I am looking forward to this series since its a new idea that doesn't follow the standard cliché.