I'm often in RvB and you really don't earn isk while there.
The cycle is:
1. Join RvB
2. Fit about 10000 ships ready for combat
3. PvP like a madman for awhile until you are low on resources
4. Leave RvB to make some isk
5. Go back to step 1
I personally have made an art form of making low cost effective ships to fight with. Just about all hulls used are T1...whenever somebody undocks anything real expensive they tend to lose it.
Got a force recon cruiser yesterday with a gang of mates in T1 frigates and a stabber. The killmail was worth 187 mil while the five of us combined we worth about 50 mil tops
And then there are all the 3rd party WTs that mistakenly think they can war dec us and then undock
Might as well spend 100 mil and go afk for a week before war deccing 3000 constant pvp pilots in the RvB alliance.
Also we don't pod each other, so it keeps the killmails reasonable inexpensive...you only lose your ship.
RvB is by far the most fun I have in EVE. I can log in, pick a ship (usually rifter sometimes I fly intys, I have stealth bombers docked all over our systems for when BS's get undocked...), undock and can usually have a target readily available.
It is pretty good mannered...there are tears of course but it is EVE....tears taste great....