The lie is the weapon used most often by the criminal.
That’s pretty much the crux of it.
I think it is human nature to strive to improve one’s situation - which usually involves dealing with others and convincing them that it is in their best interest to make the deal.
But what if it’s not in their best interest to make the deal? What if it would be a mistake to hire you? Do you admit your shortcomings in the job interview, or admit the product you are trading is worthless?
No, people with nothing to offer need to survive too, so they lie.
This is why the Democrats, the Communists, the criminals tell nothing but lies. They can’t tell the truth because the truth is that they are selling is worthless - or even poisonous. They need the deal to go through - and telling the truth would kill the deal - so they lie.