The OP makes some very valid points.

Sadly when money is involved it can change a person & greed can take over.
people should really see bitcoin in the same way they see physical fiat or precious metals, something that should be secured to prevent theft.

Thieves do not just exist in the real world, cyber crime is now more than ever a very real and increasing risk.
Due to how bitcoin works once they have been taken there is very little chance of getting them back.

However its not just theft that you are securing yourself from.
As computers can be very temperamental at times and if your storage device was to corrupt you would lose your bitcoins. By backing up your wallet regularly you can minimize this risk.