But we don't know his story yet why he bet that amount of money. But even you bet small money possible all your capital will gone if you do not know how to handle it.
The story why he bet $1.5k 2 times because he wants to recover $800 his losses before (it already stated on the title). With $1.5 bet on 70% win chance it means he took around $450 from each of winning bet.