I feel like I started to focus more on RP after I obtained the things I wanted. The wedding ring when my character first got married, the apartment so we had a place to live, that first awesome car I wanted.
RP happened throughout the goals I set for my character, but I didn't come into the server at the beginning knowing what I wanted or even how "RP" interacted with this game. I think that's the same for a lot of people, and the natural thing to do is to find a job or activity to partake in that you feel is most valuable for your time. Not necessarily what is most path-paving for your character (like I said, I didn't even know what my character was like yet).
After that's found, the other things happen organically. Running that red light, going a little too fast, and getting caught by police while trying to deliver some peaches. Getting robbed of the few $1000 bucks I had in pockets, these are all things happened while learning about the server.
Genuinely finding a path for my character happened later, once I got a footing in how to play this "game". I realized the money aspect was just supplemental to what the RP could bring, and began to use them as tools rather than caring about their monetary value.
I think there's a hard lesson learned when we talk about putting RP before grinding, etc. It's not a simple answer, and the only way it really can happen is by putting value on things that aren't reliant on money. But rather, reliant on player interaction. Perhaps the high risk, high reward of bank robberies or some new drug that is only obtainable in a certain way that requires person-to-person interaction would be a sort-of solution.
I don't have the time to suggest a lot of things, but just food for thought.