We all know that most computer systems are insecure. In the past, cracking a computer could only yield things like names, addresses, passwords (hashed and salted, one hopes), confidential files... in short, information. But with Bitcoin, crackers now enjoy the tantalizing possibility of stealing money! That makes Bitcoin exchanges (and, if bitcoin becomes popular, all ordinary PCs with bitcoin wallets) highly attractive hacking targets. So how can we be sure that an exchange won't be hacked? How can we be sure that our PCs won't be hacked? This issue--my inability to know that my coins are secure--has made me reluctant to buy them in the past.
Also, what regulations exist to ensure exchanges are secure? What incentives exist to encourage exchanges to be bulletproof against against hacks (or scams / social engineering)? And finally, how can we know that the exchange itself is entirely legitimate?
And by the way, I'm sure conventional large banks and financial institutions occasionally have hacks too, which reminds me of another difference between bitcoin and traditional money management. The difference is that you can mostly trust traditional institutions to compensate customers for any funds stolen from customer accounts (as long as it wasn't blatantly the customer's fault). To what extent is this assurance available in the bitcoin world?