Why there is no proof of Muhammad living an extravagant luxury life after he became the leader of Makkah?

So I believe Muhammad used Islam to build his political ambitions, and succeeded. There is enough evidence to show he had a lustful, power greedy and blood thirsty life like any emperor. But I have hardly come across any evidence that he lived a royal life. I mean no mention of a palace, or luxury at all. And Muslims generally are proud about how humble his life was even after being a King - I mean not even an average life stule he seems to be a poor guy even aftr he conquered Mekka. But from all the other things he has done, he doesn't seem to be that virtuous to live a below par life when he is the commander of Muslims. So what do you all think?