I have not read your other answers, so please forgive me if this is repetitive. But - night time bed wetting has nothing to do with potty training. Some children have bladders that do not grow as fast as the rest of them, and there is also some kind of enzyme that one's body should produce in order to signal the kidneys to stop producing urine at night. Bed wetters do not produce enough of this enzyme. So, there's a physical reason that your son is wetting the bed. It doesn't matter how much you or he want him to stop wetting the bed, he will just have to grow out of it.
That being said, my older daughter (who is a bright, motivated kid and was potty trained at 2 years) wet the bed until she was almost 5. Then, one day it was like a light switch turning on - she just stopped wetting the bed and that was that! But up until that point, she was so frustrated and ashamed of herself for having to wear pull-ups at night. We kept telling her it was not her fault, but she knew her friends didn't wear pull-ups and it made her sad. It helped some that my husband had been a bed wetter until he was 8 (yes, really) and he understood what she was going through and could reassure her that she would grow out of it.
My cousin's little boy wet the bed until he was 7. He grew out of it as well (he's now 8).
Don't worry about it. Buy the pull-ups until he stays dry at night. No big deal. This is not your failure as a parent, nor is it your son's failure. It is what it is, and he'll grow out of it.