In many cases maybe your data is even more secure in a cloud than on your own servers, especially if you choose your 'cloud' carefully (outside of your country/jurisdiction).
The real threats to your data are your own employees and your government. The outside 'hackers' come as a very distant third.
Actually the real thread comes from the government, where the cloud provider resides. If you are running a corporation in Europe, it is probably illegal to use US based cloud providers (even, if your data stays on their European servers) for anything that contains user or employee data - and this is thanks to the Patriot Act or similar, which gives the US government the right to inspect all all accounts and their data of an US provider. And this is illegal to (most) European countries law. And since this is illegal and the European company knows this fact, the European firm can get itself in trouble, when using cloud serviced from a US provider.
Somehow the whole story is a deja vu. Remember, how encryption could not get exported from the US market? This created lots of opportunities for encryption software vendors outside of the USA. I am just looking for the global (minus USA) cloud providers to pop up and making loads of money by just replicating existing cloud models and running them in a different jurisdiction.