I've cared for a few hundred children, probably close to 300 or more if I include part-timers and drop-ins through the years. I believe this is just a personality thing. You might be able to influence him over time by refusing to go get him until he stops crying. That seems harsh and it does force him eventually to entertain himself. But this is a decision that must be made carefully. First you have to give him things he can do. Toys that make noise and start easy that are hung on the crib helps. Music in the room helps and especially anything that starts from something he's doing. Lots of people don't believe in having any toys in the crib. I think millions of people have had toys in their cribs for hundreds of years so it really can't be all bad. But you have to choose toys that will NOT fall apart.
There is no way that it would work to start doing this and then stop because you can't stand his crying. So don't start unless you can follow through.