The risk of what? Coinbase stealing everyone users bitcoins and running away? Better not use any bank, credit union, or money transferring service to stay safe.
Coinbase is a private company that is barely regulated. Any money put into Bitcoins should be money you are willing to lose.
Sorry dude but I can't down vote this hard enough. Please read about the history of Bitcoin exchanges, and for that matter the history of banks. They arent trustworthy, and become insolvent all the time. The FDIC exists for a reason.
> Coinbase is insured against employee theft and hacking in an amount that exceeds the average value of online bitcoin it holds at any given time.
If someone steals 90% of Coinbase's transiently held coins, no insurance coverage.