I can’t speak to the Wikipedia page as I have not read it but the biographical material in my Norton Critical Moby Dick and Delbanco’s Melville line up: Moby Dick was a flop and ruined his reputation in society, Pierre not selling further precipitated the crisis built from choices made while riding a high into The Whale.

Melville bought many things with debt: his farm, his rare books, clothes. I don’t find it unimaginable that he paid for the grand tour with debt spending either.