Ripping up documents is evidence of mens rea.

[MineralMan]

mens re·a
/menz ˈrēə/
nounLAW
the intention or knowledge of wrongdoing that constitutes part of a crime, as opposed to the action or conduct of the accused.

Simplified, mens rea is Latin for "guilty mind."

That Trump consistently tried to destroy documents that might implicate him in something is evidence that he knew he was doing something wrong and trying to hide that.

It's a very important part of proving guilt in a court of law.

[PJMcK]

1. Of course Trump knew what he did was wrong

He had been told that they had to preserve everything but he just didn't care or he wanted to hide what he was doing.

Remember, Trump said that Speaker Pelosi "broke the law" by tearing up his State of the Union speech. The fact that he thought that is mens rea, too.

It also demonstrates that Trump is stupid in that he conflates as photocopy of his speech with official Presidential documents.

[malaise]

2. He told everyone his intentions

The Slobfather- “Under the normal rules, I’ll be out in 2024…maybe that is a good idea”.
Presidents are elected for four years. That should have been condemned loudly.