how can it be the biggest exchange
Hack, not exchange.
Biggest in terms of the value of the coins.
when majority of people haven't even heard of it before? not to mention that according to all the exchange rankings that i have seen so far based on volume they aren't even among top 10 as far as i can remember!
If you ask 100 people in my country what is Costco or Tesco probably 1 of them will know the answer (and I'm from Europe)
Stop looking at the fake volume on CMC, they started a lot of deals with 3rd parties in Japan including physical stores after the hack and got bought by a serious investor so it might be that the "hack" was actually a real hack.
Since they started reimbursing the money (at the value of the hack, and the value decreased a lot since then), the FSA gave them their license and ok, seems like I was wrong about them a year ago when I too screamed fishy!!!