Don't judge a person by what they say or do in a single day; look at the long term. Some people have a performative personality, becoming extremely talkative and active when there are outsiders or crowds around, putting on a show to the point where they almost believe their own act themselves. In reality, they don't do anything and take no responsibility, so outsiders might think they've accomplished a lot.

I'm dying of laughter; I'll just watch and stay silent.

It's only a matter of time before this kind of person is exposed.

Whether the shell is solid or hollow will be revealed with just one fall; it's inevitable sooner or later.