I got results on my chiari malformation said 6mm below something and the nuero surgen doesn't want to do surgery why?

Surgery not needed. A chiari 1 malformation is not a dangerous condition, but can cause headaches, numbness, dizziness or unsteadiness. In yours, the cerebellar tonsils lie 6 mm below the foramen magnum (the hole at the base of the skull). This is fairly small and not dangerous so the only reason to have surgery is to relieve symptoms. Often the symptoms and the chiari are unrelated so surgery doesn't help.
Not always surgical. Not all cases of chiari 1 malformations need surgical decompression. The surgeon will use your exam and history to decide if you would benefit from surgical decompression. I personally wait until the patient's symptoms are beyond just headaches since surgery is not guaranteed to resolve headaches.
No brain crowding. I presume the reason for not wanting to operate is that the cerebellar tonsils protruding through the foramen magnum were not crowded and under pressure. You need to speak to the neurosurgeon to get their opinion.
I agree. Surgery is for decompression if the cam is compressing brain or spinal cord, not otherwise.