You may be smart in your peer group right now, but there will always be someone smarter than you are, better at school, etc and hopefully you'll find the group one day where you aren't "smart".
I think that therein is the value of finding an intellectual peer group for HG+ kids. My dd13 was never one to make comments that could be construed as bragging (other than answering honestly when parents would ask stupid questions like, "my dc is reading at this level. What level are you reading at?). However, she's been distinctly not big headed about her smarts since skipping a grade.
That put her with a group that was, on average, 18 months older than she and some of her friends in grade are about two years older (combo of bd that just made the K cut for dd and the skip plus a lot of redshirting in our area). She also found at least one HG-PG friend who is 18 months older than herself in middle school and who is immensely strong in math, which is dd's weakest subject. Pre-skip, even though it was her weakest subject, she was often in the situation of being the most able and high achieving in the class in math and serving as a teacher's helper.
I'd say that a combo of talking with him about it and actively seeking peers for him so he gets a broader perspective than the big fish in small pond mentality may help.
