Have you found out what Napoleon's salary was as First Consul and then Emperor? Seems to me that might be relevant to the argument. Your sources for your investigation might be interesting also.
By the way, how much wealth was in personal possession of Francis I, Alexander, George III, and Frederick William and how did they acquire it? Do you have salary figures for these sovereigns?
Another aspect you might want to look at is how much internal improvement went on in France compared with the other major nations of Europe at the time. What percentage of the respective populations were impoverished and were starving compared to the wealth of the respective sovereigns.
It has been noted elsewhere that Napoleon saved approximately half his salary as Emperor and that he was quite frugal in his personal life with definite ideas how long his underwear should last, and that he ate simply and very quickly. He also built no new palaces, but greatly improved the infrastructure of France. What did the other fellows do during the period?