The Bitcoin network and currency has proven to be secure, functional, and efficient. The technology used to build Bitcoin is mathematically secured by the laws of the universe, and is constantly being improved upon by the open-source community. The software is actively inspected, and audited by this growing community.
Though there have been Bitcoin-related compromises in the past, this does not reflect upon the security of the Bitcoin network itself. Bitcoin-related thefts are usually the result of improper security or negligence on the part of the person or service holding the bitcoins. If you left your wallet on a park bench and it was stolen, it would not be considered a "hack" of the dollar. This is why it is important to trust the security practices of any Bitcoin-related service you use.
As more stakeholders become interested in the success of Bitcoin, the system will become more secure, as increasingly significant resources are being devoted to closing security holes and thoroughly vetting any proposed changes.
As a holder of bitcoin, you have tremendous power over your money. Because of this, it is important to follow good security practices to protect your funds. Since most people are not specifically trained in computer security, Coinbase can manage the bulk of these security measures on your behalf.
At Coinbase, we're committed to security by using industry best practices and storing up to 97% of bitcoins in encrypted, geographically separated, offline storage. To further protect our customers, all of the bitcoins stored in online computers are insured. Digital currency is not legal tender, is not backed by the government, and digital currency accounts and value balances on Coinbase are not subject to Federal Deposit Insurance Corporation or Securities Investor Protection Corporation protections. Even with these safeguards provided by Coinbase, we recommend you take further measures to secure your account against unauthorized access.