It is a big win from $10,000 initial bet to final win around $550k. It's x55 win for the winner. The user would be rich enough to make that $10,000 bet and were afford to lose $10,000 by betting.
Not to mention that this guy bet 10K on a parlay bet with 55 odds with spread points on all the match included. He probably doing this bet multiple times and successfully win one of his parlay. A person that doing a normal high bet will definitely not gonna place that huge amount on a single parlay.
He is very lucky to this bet because NBA matches during near playoffs season is usually very unpredictable since team is motivated to qualify.