Well, that's arguable I think. If you're 100% sure computer wise then bitcoin is safe as long as you don't make any big mistakes like .... sending to the wrong address, but these things seem to happen to a lot of people right now.
How would that happen? It is almost impossible to type in a valid but "wrong" address by accident. The transaction just won't go (like entering wrong details for a bank transfer)
Not an invalid address, but this guy just sent 800 btc to the wrong address just a few days ago:
https://bitcointalk.org/index.php?topic=636126.0;all
That is still shocking. I get nervous and triple check everything when sending even .01 anywhere.
Most people are not as careful with their money because of the consumer protections that other payment methods have. Bitcoin does not have these consumer protections and this is probably the greatest determent to bitcoin being widely accepted.