I'm not going to stay in contact with a guy I just met.
What's wrong with the guy?
Because I'm tired of meeting people like him every day
Then you have the right to not contact him then. I recommend you put his contact on block in case he tries to reach out to you. He will get the message after a while and leave you alone so you don't always need to make up excuses to avoid him.
He is dangerous and he will put me in danger
It sounds like you are making the right choice to avoid this guy. If you know he is dangerous, have you considered calling the police?