Errors always happen in business . Japan is considered as a country of first learners, opportunity takers and hard workers. When others couldn't find the meaning of Bitcoin, they took it seriously and made a virtual dominant currency.
I believe Zaif made real loss and we should always expect them, especially when a large amount of money is invested in the system.
I personally do not understand well about Bitcoin when performing transaction with an exchange. Sometimes back, I had decided to buy dogecoin . I did all the requirements, looked for an exchange and bought some dogecoin. At the end, I never saw my coin. It used to take some times, but that day I never received anything and lost my money.
I think the reverse can also happen with the exchange. If I can loose my coins, may be they also make errors by giving out free coins or the system may be having maintenance issues.
If they are to carry an investigation, they will discover the lost coins, but surely they may not have the power to bring back their coins unless the person is deeply concerned and bring the coins back.
P.S: It's always my joy to see Bitcoin growing and it's value raises other coins value which makes the market a bit profitable.
how can he steal 20 trillion when all of the crypto currencies put together are worth under 500 billion doesnt make sense
He can't, it was a result of a glitch on the exchange, extreme greed, and what sounds like no knowledge of the actual Bitcoin market cap. There will be no way that he gets anything remotely close to that buy order and I doubt anything at all since the rest of the trades we're cancelled.