RMT is essentially dead on tarkov (good for them though). It will be interesting to see how it works come wipe. Only real thing you can RMT without getting raped is items dropped in raid like guns, armor, helmets, etc. All the main keys, roubles etc. are no longer able to be dropped in raid. If you inspect item, it will tell you in description that item cannot be dropped in raid.
I imagine wipe will be like, I will join your reserve raid and open RB ST for you, instead of selling RB ST key. The exception to this is of course if you have FIR stuff you can barter via flea.