Which is still easily replaced. For those of questionable morals, running BTL's, drugs, or organlegging (including the wetwork side of it) is extremely profitable. Money can flow like water in SR. While they might not hold onto it long, they can dip into the money stream and get some neat toys and upgrades out of it.
I don't agree with simply taking the money away on a whim, or deciding that they have too much of it. Present a scenario, and leave the choice of what to do with the cash up to the players. Of course, sometimes an adversary will come along that the only thing one can do is watch the money leave, but I don't recommend that as a way to "balance" cash flow.
If you don't like the karma for cash, that's fine. It's not for everyone. I just like the flexibility and choice it gives to my players.
Dude, I don't even have to be cruel GM to think of ways money can disappear in Shadowrun.
Hell, money should be tight for the PC's anyway! Maybe I am just an old skool Shadowrun GM but having too much money should not be a problem unless they paid for that money in character creation with a lifestyle choice!
Shadowrun is still dystopia right? Still SINless (a money dump in itself) individuals trying to eke a living while sticking it to the man right? I guess I am saying that figuring out where to spend all of the money should be the
least of their problems! Pissed off corps, rival runner teams, paying to stay anonymous, pissed off organized crime when those enterprising Shadowrunners start selling drugs and undercutting the big boys.
As much as I think karma for cash is a bad idea, I don't even see where I would have to use that!
I think some of you may be paying your runners too much money!

But like I always say, your campaign may vary! If you are having fun with Shadowrun, that is really all that matters.