The US team threw their game with Belgium because they didn't like Trump's thumb on the scale
The player that received a red card and had it taken away at Trump's request is Folarin Balogun, and he's a birthright citizen. His pregnant mom got stuck in the US as a tourist and ended up having him in the US before returning to the UK. Trump was recently pissed about birthright citizenship being reaffirmed in the US Supreme Court, but apparently thought the glory of the US soccer team was worth asking FIFA to revoke the red card given to top player Balogun. It probably felt like whiplash to hear the president say people like you shouldn't be a citizen and then fight so hard for your right to play in the round of 16.
My theory is that the US team wanted nothing to do with Trump and didn't want to advance so far that they were invited to the White House, especially if there was controversy about one of their players being allowed to play in a pivotal game after a red card. By throwing the game, the red card controversy becomes irrelevant, Folarin Balogun is out of the spotlight, and the US didn't finish their World Cup run impressively enough to be invited to the White House and pal around with a racist xenophobe.
Further, there were probably bets made at more distant odds for the US team to win against Belgium before the red card revocation was announced. More distant odds equal a better payout, and Trump could have certainly passed along inside information for sports betting and prediction markets. By losing and losing badly, any possible inside traders that bet on the US either winning or having a higher/closer score because Balogun was back in play are SOL.