Is it really believable? I don't think someone to lose that amount, nobody does in just one session.
Besides, you have noticed that OP hasn't complained about his losses, and never felt regret or sad about the results as it was easy to make a story that never happened in real life.
Anyway, losses are usual in gambling and if we can't control our expensing habit, losing more is very possible. A reason why we should have set limits on the amount that we can spend in one day.
We do not really have a way to know and personally I would prefer that it was not real, since in my case it would really pain me to lose so much money over such a short span of time, however we have seen people like Drake losing way more money than that before, with the difference he is incredibly wealthy, but this makes me think that even if the story of the OP was not true, there are probably many gamblers out there which have experimented those kind of losses before.
It looks like I keep losing more and more money every new gambling session I take playing slots so I decided to quit for good and to follow only sport betting.I also am not that knowledgeable in that area too so I just prefer to copy other people bets.When I do so I check the odds,if the odds are low I copy the bets no matter that there are a lot of games into a ticket.
I have not lost a large amount of money in slots,no more than 100-200 dollars but that feeling is the same no matter if you lose 200 or 200.000 if you keep hitting those red attacks on your balance.