He kept wondering why people who had so much money were never satisfied but were always wanting more.
这里的but  

如果用on the other hand 可以吗?
即:He kept wondering why people who had so much money were never satisfied ,on the other hand,they were always wanting more. (还是要用on the contrary?)
问题补充：或者用 whereas 可以吗?
既::He kept wondering why people who had so much money were never satisfied whereas they were always wanting more.
这句还可以说成:He kept an idea why people who had so much money were never satisfied but were always wanting more. 吗?(我觉得这样讲也能表达原句的意思) 我不知道这样的讲法是不是符合英语习惯?