I took up roon’s lifetime 4+ years ago, and don’t recall any referral program back then. I’ve recommended it it to many and never really thought about what is in it for me, never mind the 1000’s of people myself and others help here every day with their roon installations and operational troubles.
I get so much enjoyment from picking up a device and playing music wherever I happen to be in the house.
I have a friend who started using roon a few years ago now but he is not a fan of how it does some things yet it keeps being used and renewed in his setup - and I am happy to help him when things sometimes break or he needs to tweak something.
I think the what’s in it for me attitude for something like roon is better looked at by saying what’s in it for someone else IMHO ie how can I let someone else experience something that gives me so much enjoyment.