But yes I am like other posters, don’t be a dick head.

If you do not want people joining your workouts. Then quite boasting to your “friends” about how much you know about lifting weights and the correct training methods and correct use of form.

If you would stop being a know it all on these subjects, then people would not be curious and want to join and learn.

Yeh your buddy probably stroked up encouragement to ask if he could join. So don’t be a dick. Let him workout with you once or twice a week. Besides muscles need different workouts. So switch it up, it might benefit you more then you realize. Muscle adapt to routine and do not pass the next threshold until you change your habits.

And don’t make it a habit of being a dick.
Unless you want to be alone with no friends. Which I prefer, but I have needed to be a dick to accomplish this goal.