I feel like there is a big misconception about masking in the community, especially in the younger circles.
When you look up resources on ASPD/NPD, you are mostly hit with people being like "psychopaths ARE PRETENDING TO BE SOMEONE COMPLETELY ELSE but when you are with them THE MONSTER COMES OUT".
I feel like that thing subconsciously went into the minds of people with those disorders, especially if you are self-diagnosed and have to rely on resources you find on the internet and in books.
Masking is not carefully picking out a personality and then acting every time you meet another person. Of course, it could look like that, but those cases are rare and definitely never kept up consistently because it's so exhausting. Can it be fun to do on a night out where you don't plan on keeping in contact with anyone? Sure. But constantly, you just won't manage that, especially if you are more extroverted than introverted or if you have many social interactions for other reasons.
It's also not masking if you are acting different at work, around children, around your friends or around your closest people. That's completely natural, everyone does this, even people who do not have a cluster B disorder.
Masking looks more like covering up negative symptoms of your disorder. If I really don't give a shit about that persons relative dying, then I will obviously not tell them that. Masking is covering up the lack of empathy, sympathy, impulsive thoughts, violent thoughts, anything people might consider as "immoral". It's more knowing what to keep to yourself than actually making up being another person.
I feel like some people feel some sort of pressure on them to make their masking game perfect, even though it's really not that deep. You can show people who you are. You can show them your passions, what you love, what your dreams are. Maybe don't tell them if your passion is seeing people's guts falling out, but you have so many positive attributes too, you don't need to hide that.
I'm not talking about masking of autistic people, just about masking in cluster B personality disorders, as I am not autistic and can't talk about that.