Everyone can be a great guitar player. It just needs a lot of time and dedication. When you see someone younger then you and better it only means that he put more time and effort in it, thats all. So take him as an example instead of comparing yourself ;)

Also, heres a thought that might ease off the pressure you put on yourself. Eventually we all die and we dont bring our guitar skills with us in heaven :p
So have fun for the time it last ... without comparing or judging yourself.