Sounds like it should really be a page or a group and you risk losing it if you're ever given the "Photo Challenge"
If facebook notice unusual activity on your account they may ask you to identify your friends in group photos. I'm not sure you could do that for most of your 5000 friends.
Wow, I didn't know they did that. I don't use my Facebook for anything but friends and family. For those who have a lot of followers that would indeed be quite the challenge to identify everyone.
Better create a fanpage or a group in a specific niche and then deliver them content and some offers from time to time
Try to use Facebook ads. And it's better to create a group like it was mentioned above. On the whole it's easier to monetize Instagram than Facebook. FB now is full of strange things that only interrupt using it.
Sigh... people have no idea how to monetize Facebook. If your friend actually has that many fans, he needs to create a fanpage, move people to that and just keep being himself to grow it. Once he breaks 10K fans on that page, send me a DM and I'll tell you how to monetize it.
It can give benefit if you still maintaining your friendship with them all. Say hi, like, comments on them profile to get them view your content.