Why? Because there is no way it can help you. It can only hurt you.
For instance, if you make an inculpatory statement (one that suggests you might be guilty), the prosecution will use that against you at trial. It’s admissible as a “statement by a party opponent” and the jury will hear your admission. On the other hand, if you make an exculpatory statement (one that suggests you’re innocent), the court will not allow the jury to hear it on the ground that it’s self-serving "hearsay."
Does that sound like an unfair double standard? Yes, but it’s the law and it’s used every day against people accused of crimes. Thus, nothing you say to the police can help you in a courtroom.
U.S. Supreme Court Justice Robert Jackson (1892 - 1954) once said that “any lawyer worth his salt will tell the suspect in no uncertain terms to make no statement to police under any circumstances.”
If the police want to ask you questions, just say, “No, Thank You, Officer.”