The hacking events at the FDIC were aimed at gathering "economic intelligence" rather than gaining access to currency transfer. In any case a FDIC insured bank retains liability for any funds you lose in a bank failure and they require that banks have commercial insurance to cover any losses resulting from theft, computer failure or other events.
Despite a hack of the FDIC, in general money is safe in the bank. If it were not, chaos would ensue. Accordingly, even if some malicious assault on the FDIC's systems was successful, the Federal Government would expend an enormous amount of resources to get the system back on line.
While digital crime is always a worry when it comes to personal finances, it is still much more reliable and safe than keeping it under a mattress. With a bank you always have back up protection to an extent, which you wouldn't have otherwise. It's much better to let the bank take care of your money.
No, money kept in banks is not safe. As bank records move from paper records to electronic storage methods, hacking becomes a very real threat that can mean the difference between secure bank accounts and accounts being drained. Banks should be required to keep paper backups of all electronic banking records.