Here's what I mean. On his Charley Project it's stated that Jacob was seen getting gas two days after his disappearance
1,000 miles from home. Meaning, he had his car after his disappearance and he was in some kind of hurry to have driven 1,000 miles in two days.
http://www.charleyproject.org/cases/c/cabinaw_jacob.html
I didn't personally know Jacob but I live in the same place he disappeared from and I know the culture, the economy at the time he went missing, and some of his acquaintances. I believe that Jacob did leave willingly, possibly to make some quick money, and that he had every intention to be back home soon and that in the end, foul play
was involved and that's why no car or Jacob has been found
Like I said, I didn't know him, and I don't know if he's lived here his whole life, but this is a sort of innocent town with not a ton of money to be made for the working class. If my theory is correct, he probably didn't realize the sort of trouble he could get into along the way.
There have also been theories that he's in some sort of fugue state but I totally doubt that. After 4 1/2 years someone would have seen something.
All my opinion, of course.