It may be possible to recover from psychosis without treatment but that is the exception rather than the norm. Generally, untreated psychosis becomes worse over time. Individuals typically continue to experience symptoms until the psychosis is treated. He may seem “okay” right now but you may not be seeing the full picture. His unwillingness to seek treatment is concerning as is his drinking. Alcohol and other drug use can exacerbate psychosis.
Based on information that you have provided, I do not think he is well. He needs treatment. Psychosis does not generally improve on its own. In virtually all cases, treatment is necessary. Without such treatment, decompensation occurs.
This is a very challenging situation. He is an adult and as such it is difficult to force him into treatment, especially if he does not want it or does not think that it is needed. Unfortunately, in many states, the only time that you can force someone into treatment is when they are on the verge of seriously harming themselves or someone else.
My recommendation is to try to convince him to seek treatment. I understand that he may not be willing but it is worth a try. I would also recommend attempting to connect with other friends or family members who are concerned about his condition. He may be willing to attend treatment if several individuals share the opinion that he is not well.
Two websites may be of assistance to you: the Treatment Advocacy Center and the National Alliance On Mental Illness(NAMI). The Treatment Advocacy Center provides information about state civil commitment laws. Their website also provides information about how to handle psychiatric emergencies and when to call for help. NAMI may be a helpful resource because they provide educational information about mental health disorders as well as guidance about navigating the mental health system. NAMI has support groups for family members who have a loved one with a mental illness. Most communities throughout the United States have such support groups. I wish you the best of luck. Please take care.