I think it's really hard to paint all kids (all boys, all girls) or "all anyone" with a broad brush. Think about how awful it has been to be told that "all women do X" or "all women are too emotional" or whatever. It's insulting. So we have to allow our kids the same breadth of personality types.
If he's not depressed (which his participation seems to indicate he is not) and if he is showing some recognition that some things are a big sacrifice, I think he's fine. A lot of kids struggle with hormonal changes and try to keep things in control, and a lot of them see people who are overly excited or dramatic and so they make a concerted effort to NOT emulate them.
If you are doing the sports events and the camps because you can easily afford them and you enjoy them too, fine. If anyone in the family, however, is paying for these because the "ordinary" stuff doesn't get a rise out of your son, I'd suggest they rethink that. Be sure no one is trying to "buy" his pleasure or expect him to react in a certain way.
I do think the point below about being "gushing" enough to thank people for gifts is important though. The inability to show gratitude and appreciation (or a very narrow definition of what constitutes an appropriate response) will hurt Grandma's feelings, but also play out poorly dating, in job or college interviews, in interaction with a police officer who pulls him over in a few years and lets him off with a warning, and in interactions with a boss who just gave him a raise (summer or permanent jobs) will come back to bite him. So some schooling in "etiquette" (and I don't mean which fork to use - I mean basic manners) is a good thing.