Maybe just send a card next year and not a present, it shows you are still thinking of him. If he is too self-absorbed to return the thought, then he won't (or shouldn't) notice the absence of a gift you have taken the time to post.
And when he finally grows up, and starts thinking outside his small circle, you may start receiving cards again, which will be nice for you.
In this electronic age it is still nice to receive a card though the post, and I am sure the younger generation like receiving them too. However without lumping them all under the same umbrella (because they are not all the same), there are some who are just me me me. They don't think about returning the thought by sending cards. Whereas other do. The one day that younger (late teens, 20's) will send cards is Valentines. But again this is sometimes more about the sender than the receiver.
Years ago I sent my nephew (and his new wife) a lovely cut glass vase as a wedding gift. The one time you should send thank you notes is for wedding gifts, but no card, no email, no text nothing to thank me. And no acknowledgement of this year's birthday present.
I know there will be no thank-you next year as I have decided to stop. There are no problems in the family he is just not thinking of others.