It really seems like he would have all the resources and manpower needed to crank out ships, so how did the British maintain naval supremacy?
I've written about this before.
https://www.reddit.com/r/AskHistorians/comments/2709jm/how_would_a_britishhms_frigate_built_in_1715/
https://www.reddit.com/r/AskHistorians/comments/4xurpx/how_did_napoleon_plan_to_invade_england/
https://www.reddit.com/r/AskHistorians/comments/3pn7v5/what_changes_occurred_in_the_construction/
The tl;dr is that what John Keegan calls "the price of admiralty" is extraordinarily expensive -- Napoleon faced many foes on land, and never quite understood the expense of not only shipbuilding, but the time required to train and equip and refit a fleet that would challenge the Royal Navy, while Britain, being protected by its island status, could maintain a fairly small army (relative to the RN) and still effectively form an alliance against Napoleon.