There were a number of American factions pushing for war in 1812. Many merchants had expanded their businesses benefitting from the wars in Europe. Hence my earlier point about the quadrupling of the merchant marine. There were also the hawks that thought it would be fairly easy to free those poor Canadians from the British yoke. And there were a quite a few that thought that British interference in US affairs was an affront to national pride.

And there were those who traded regularly with Canada who would be ruined by war and so opposed it.Some merchants of Eastern Maine even made a separate 'peace' and signed a temporary allegiance to King George.

And there were many many more who didn't live near the coast or the border with Canada who had no interest in the war whatsoever.

Initially the merchants could fit out privateers and make a handsome profit from capturing British vessels. But later they found that their privateers were being snapped up by British cruisers, and their goods rotting in warehouses because of British blockade.