A French user who identified himself as Théo, a former US banker who bets on multiple accounts, has bet more than $30 million on the Polymarket platform to support Mr. Trump's 2024 election, saying the move was "apolitical" and purely for profit. If Mr. Trump wins, he will earn more than $80 million; if Harris wins, he will lose most of his money. The investment is almost all of his current assets.