It's not the first time we have seen these type of people who can't handle their loss and start blaming casino for their own mistakes but you see in the end they gain nothing out of it as @Hhampuz already cleared it above as this is one of those fake accusations.
It's because many gamblers can't accept that they lost significant amount in gambling and then they will accuse the casino (in general) that they got scam. This is the problem if you risk the money that you can't afford to lose, it's really hard to accept the bad result specially if you're expecting the opposite.
Anyhow, if the accusation has basis and legit, there should be concrete evidence to back up the claim in order to address the issue.
Thats such a sad situation. This is gambling, of course you are going to lose your money here and that should be the first thing that you accept when you get in here. I remember in early crypto days there were people who thought that the system was rigged because they played dice on 50% and they would lose 10+ in a row, and try to make a calculation based on how rare it should be and unlikely it should be.
When in reality each bet is still 50% and the longer you play the bigger chance you get to have a big losing streak, thats just normal. This is why I believe people who complain on things that are provably fair are just people who are not really realizing the reality of gambling.