I was considering to invest in Bitcoins but seems like it is not secure.
Is there any method to protect bitcoins from a robber.
31 Bitcoins ($ 12,090.07) What a huge amount of loss to Edward.
Yes there is! For such a huge amount, OP should have used paper wallets or have bought a hardware wallet like a Bitcoin Trezor. Any of these two combinations is perfectly safe and should be used for anything over 7-8 coins in my opinion.
OP sorry for your loss by the way!