100% agree if the blockchain lacks the require tight security all coins with the same algos should have been hacked long ago this kind of news only happens once in a blue moon or rare, so it is better for us to look for a better exchange that guarantees security to their network, even banks get robbed.

There is a difference between lost and stolen (it may be the same for the one who lost his Bitcoins but the impacton the market is not the same).
Lost Bitcoins will make BTTC pice rise because the circulating volume will be reduced while stolen Bitcoins will not affect the market because it will be used and sold by someone else.

If your bank was hacked, would you suddenly lose faith in fiat currency? Would you suddenly convert all your fiat currency into bitcoin? No, I highly doubt it. People need to stop blaming bitcoin, it isn't bitcoin that is vulnerable to hacking, it is the exchanges that don't properly secure their assets. Similarly bank heists used to be much more common until precautionary measures were taken. A few events like this will make bitcoin stronger, as security protocols around its storage are bolstered.

Well you might be assuming it could be a fake story until you send some coin to unintended wallet. This is really why we should be careful with our dealings.

Since Mt. Gox lost a lot of bitcoins in 2014, we have seen the frequent hacker theft of coins on these exchanges, so now I don't believe in the exchange, and all my coins are stored in my wallet.

Is NEM open source?

The coins are still stored in the Blockchain, they just shifted from their original address to another address not owned by the account holders on the MtGox exchange. You cannot remove any coins from the Blockchain, but you can mix the coins up a little that they cannot be traced back to the original owner. 

As a matter of fact, you might be using some of the coins that was stolen in the MtGox hack.  The exact same thing happens with cash, you will never know where that cash was, before it reached you.

It is just a known number from single source but the real number of lost Bitcoin is much more than this number. We don't have the mass awareness regarding the usage precautions while using cryptocurrencies and hence some people make mistakes resulting in a irrecoverable loss. Even there are theories claiming that Satoshi's Bitcoins are lost but that must be the different case.

Mt gox was stolen indeed, but they should able to track the hacker address right ?
such massive wallet hack should not let running free in cryptocurrency world. It will causing the price to drop if they dump it.