I was not playing this mod from the start, and I have busted my ass to be a Generation 4 character with a single MW item, and that is it, yet I still have fun with that character as well as my other alts (And I do not retire my alts, I don't see the point).
Money will not be an issue if you wear what the majority of player wear, 25K-35K of gear.
If you want to make money fast, wear less. If you want to barely make money in the long run (and have ups and downs) then wear 40K or so. You can sustain 25K of gear per multiplier, and your average multiplier is a little less then 2, statistically.
As for people leaving and rejoining, that rarely does anything. If the autobalancer (and I have yet to see this behavior that you describe, it is mostly new players joining a server) sees a person join it will often "swap" them to the losing team (one of the few things the autobalancer does correctly more often then not).
Your bank account should not be withering away unless you think you reserve the right to wear top-end gear 24/7. This game does not work that way, as that is bloody damn boring to see everyone wear the top gear every battle. We did that once, and the game broke.
Individual skill matters. If you contribute to the team then your team has a greater chance of winning (and thus a higher multiplier). If you are one of those leeching fools then you are a hindrance to your team and increase the chance of your team losing thus a X1 multiplier. I hate peasants who think "Oh I can't help at all I will just leech," as to be perfectly blunt that "fucks my shit up."
cRPG does have a steep learning curve, I admit this, but it can help you a lot if you start seeking out advice and not try and learn to swim all by yourself.
The fact that you are having money issues starting at level 25 or so and consistently losing money means that you have no idea what the hell you are doing, in all honesty.
If you do not view Heirlooms as worth retiring, then Don't Retire. Miley is Generation 1 (has never retired, ever) and is to this day pretty happy. There are countless other players. Retiring is door number one, not retiring is door number two. Honestly you can remain competitive and never retire, you don't have a small edge from an itsy bitsy increase from heirloomed items, but you do gain an edge from having slightly higher stats.
I highly reccomend you start asking around before you quit cRPG and try and get a better grasp on how things work. Yes, there are issues in cRPG, but Money should never, ever, become one of them, period.