B.H.
He may be physically ready but not emotionally ready.
Also to know if your son is physically ready he should be waking up dry at naptime and most mornings.
Lay off for awhile and act like you don't care. Then after noone's talked about it for a few weeks have a older child, neighbor, cousin ,or adult act like they are the coolest thing in the world and that your son is just not as cool like it's a big kid thing to do...
I told my daughter she wasn't gonna get to go to preschool and couldn't do this or that because she wore diapers it hurt her feelings to point and was a little harsh but worked great. She was also at a home daycare I worked at and it turned very competative between her and two other boys the same age and would literally fight over who got to go potty first. They were the "cool" kids at daycare.
Also pull-ups are the worst invention on Earth. They make it so incredibly comfortable to use the bathroom in them that kids don't care. Try diapers to underpants leave out the pull-ups.
Have you tried letting him wear underpants and be uncomfortable for awhile? My daughter hated being wet and cold and I'd pretend I didn't notice for a few minutes I never ran and changed her real quick. Then I held her responsible for her accidents she had to do it herself or help out big time with cleaning up and changing her clothing.