I am level 20 with my highest account with $1B in the bank and rising. My 19 level account is $550M and rising.
Smart player purchases and the fact that I have already built the world stadium and the upgrades certainly helps.
What helps the most is tanking. i can build players up over two seasons and not have to always purchase players, which at $106M being the most expensive and really only the ones you should buy for fast training, is a huge bonus.
also having a roster of 21 instead of 22 helps as you have that extra spot available for signing your youth player every 12 days for that extra money.
All that to say that I have seen players at level 20 with $-300M, so it all depends on your playing style.
BTW, I dont buy tokens. I tank!