If it's beyond your firewall, it isn't secure.
We can moan all we want to about idiots being the cause of the breaches that have resulted in
- Target compromising millions of customer credit card data
- The tens of millions of people whose healthcare information has been breached by US insurance companies
- The people affected by the OPM data breach
but the simple fact is, if it is on the internet and somebody with enough leverage wants it, they'll get that data. It's the asymmetry of the attack surface.
Oh and about those "private" services for businesses and government? Yeah, they're not all that much safer. On Monday I had to wipe an employee laptop because on Friday AV scanner on the GMail service was down. Yep, he got a virus. Yep, ransomware. Yep data has probably been lost. Yep, he was given an external USB drive to backup his data. Yep, it was hardware encrypted. Yep, he forgot his password a couple months back. Nope, we have no idea yet what his actual backup status is.