Yes, people tend to blame others for their mistakes and failures. That's just the way their brains work. More precisely, they are not smart enough to understand their mistakes and accept them properly. This is a poorly developed intellect. There's nothing you can do about it. You just have to pass by if you encounter such characters in your life. I know a few of these people. I've come to the conclusion that it's better not to have any contact with them at all.
Blaming the house is irresponsible, players are better off owning up responsibilities, and accepting results. Players who blame the house always have lesser energy and end up with a crushed problem solving skill, which won't be nice at fighting the little issues or signals that walks a player into problem gambling.
Yes, of course it is, but players accumulate negativity and they just want to put it somewhere. Professionals keep this negativity under control or just philosophically treat it, even laughing at themselves, because they understand that their created and invented strategy is really what helps them win. Therefore, you need to learn from the professionals, but I understand that it is easier said than done, so it took me years to calmly accept losses and understand that they only happen in the moment, and what is important is what will happen if I do this thousands of times and do not make gross mistakes that can appear if I start to react too emotionally to the game.