What needs to be done:
Leave the game exactly as it was before (years before) + make RP cost a little less and capsule probabilities increased.
People do like gacha. There's nothing wrong with paying for the possibility of winning a nice weapon with op status or some cool fits - just make it easier to win (exemple: instead of a lucky box after 10 spins or whatever, you get a guaranteed item from that collection)
"Oh but the game is not going to be balanced for those who don't spend money on it" - how many CSD rooms were happening before? Lots. If you don't want to play against people with RT weapons, play at a CSD room. - PS: the weapons status can be altered a little bit so it's not SUPER op as well, but still stronger.
+ make exclusive content for MP-only as well, like OP MP weapons on the capsule - this way everybody wins.
Trust me, you're going to make A LOT more money this way, and A LOT more people will play the game. Nobody is going to play the game and buy RP the way it is right now. period.