I just don't understand why people keep large funds locked up in exchanges. If you are running a business, keep just enough to cover daily transactions online, and each day set aside 15 minutes to execute the necessary deposits and withdraws.
I'm a poker player by trade, and I don't bring my entire fucking bankroll when I play, because I know when I play I might get robbed or followed or god-knows-what. I have cash at home and in safety deposit boxes and I have good credit with many casinos. Most of my funds are directly and only in my control, but I know that for ease of use, some funds have to be in other people's control. But I accept that I may lose those funds, and I only keep the bare minimum with other people.
Similarly, I spent a lot of time and money getting set up on PokerStars (I'm in the US) with fake docs, vpn, mail and phone forwarding, and a reliable route to get money on and off the site. I keep the bare minimum necessary to play actually ON Stars, because I fully expect my account to be shut down sometime in the future. I have it spread out in Moneybookers, ukash, linden dollars, other poker sites, prepaid credit cards, liberty reserve, and of course the majority is in bitcoin. If one of these shuts me down, it sucks and it's a loss, but it's not the end of the world, and I am able to keep going. I have spread myself out. Heck, I may even start a side business of currency trading!
The point is, when you are running a business with inherent risk (this includes handling lots of money), you need to be secure. I have chosen the putting my eggs in many baskets method, but I concede there is merit to the Mark Twain method ("put all your eggs in one basket AND WATCH THAT BASKET!").
But absolutely no method of security should involve having the majority of your working funds sitting on an exchange, or anywhere that is not directly and ONLY accessible by you. That's just negligence.
There are plenty of ways to invest your money or use your money that don't involve that type of risk. You want to invest? Great, pile your USD into bitcoin and let it sit in a brain wallet for 5 years. You want to day trade, great, day trade, but make sure the money is back in your account at the end of the day. You want longer term investment? Ok, then go with the biggest most corporate giant chain out there, because THEY can afford a hit, don't want to risk any smear on their reputation, and your small potatoes can easily be paid back. Plus, security in numbers.
Whatever you are doing, make sure you understand the potential areas of risk, and how this affects you. I have yet to see a bitcoin theft that wasn't caused by negligence and I have yet to see victims who didn't simply have a ton of money sitting on an exchange or on a computer accessible by other people (or a computer not firewalled or av'd).
When I want to convert USD to bitcoin, it's deposited, bought, and sent to my wallet in the same day, preferably in a few hours. And it's done in chunks, so that if there is failure, only the current chunk gets caught up in it. I'm not saying you need to do this, but leaving 5 figures or more just sitting on an exchange when you only need a fraction of that to do your business is just dumb. And if you do need all of it for your business and you don't have other reserves, you're just plain gambling too high without the proper bankroll. That's on you.
Bitcoin is as secure as it gets if you take the most basic of precautions.
Why aren't you?