Why is it abnormal to have no friends if it is normal to be gay? Don't you think eventually it will be normal to have no friends?

It will get better. This is an interesting question. I'm not sure why you compare being gay with having no friends but I'm guessing you feel both are true in your case. Normal is not a useful word in this circumstance. There is nothing abnormal about either but to live a happy and fulfilled life involves accepting what you are. People respect those who are honest about their identity and friendships flow from that.
Are you. Comfortable/satisfied with the status of your relationships? If so, it doesn't matter what someone else considers "normal", we are all unique individuals. If you are not satisfied with the status of your relationships, if you feel depressed, if you have excessive social anxiety or fears, it might help to talk to a professional about your concerns.
Most. Most people like to have other people in their life. However, there are individuals who prefer solitary activities and who may have little or no interest in being sexually active. They may not desire close friendships or even feel especially close to family members. This may be the case whether they are heterosexual or homosexual. If this is what consistently makes that person comfortable than that is his or her norm. We are all unique.