And sorry but playing computer games with your mates when you're in separate houses in your pjs is NOT socialising. I actually think it's quite dangerous to suggest this is any way just 'normal' teenage behaviour. I have teenagers and I would be concerned they would be seriously depressed if they behaved like this.
I'd love to see your GP's reaction if you dragged a 16yo to the doctors with this problem - "my son is depressed, he loves playing video games in his PJ's with his friends online". It's perfectly normal behaviour, just like playing football in the park is normal, or going to the gym is normal. People enjoy different things. Playing football isn't a superior hobby to playing video games!
'Different strokes...' . Hmmm... but what does he think about how he's spending the summer? How will he look back on it?
I look back on my lazy summers in my pjs with immense fondness. I've never been able to switch off like that since, and I miss it. You're projecting your feelings onto someone else. Just because YOU want to be out and about and achieving things, doesn't mean other people are the same.
I'm still a responsible adult with a full-time job, a house, a partner, a dog and all the rest of it. Those lazy summers at home haven't ruined my future or destroyed my chances of being successful. In fact, having that time to recharge was probably pretty vital for my mental health. Even now, if I'm stressed or tired or wiped out, nothing makes me feel better like a lazy day at home on my own. My partner would prefer to be out cycling or doing something active.
And both of those are normal preferences.