Magnitus: The sad reality of servers is that if people with the right skills really really want to hack you, you will get hacked.
The attack surface of your typical web server is huge, it is composed of many components that you won't have direct control over and while you time is spent developing the entire web site with tons of parts, other people will spend all their time examining a single potentially vulnerable part under a microscope. You might spend a couple of hours to code it, they'll spend days finickling with it trying to find a problem.
This is why proper mitigation strategies beat a "we won't get hacked" mindset any day. Things like not storing tons of user information that you don't need. As long as you make it harder to hack you than it's worth, you should be ok.
This
There is nothing "unhackable" nowadays
There have been people that have hacked into the pentagon for pete's sake, so if people can hack into the motherfucking pentagon, hack wall street, fuck up all of these stocks and shit how can anyone with a straight face say "we are unhackable"?
Sony did it with the PS3 and paid the price for it