There was a hacking attempt on largest exchange in the crypto market (with respect to volume) but hackers didn't succeeded in there plans Instead they lost their own coins. Third Party Bots were made the targets for disturbing the altcoins market on the exchange.
Image Source : https://www.nexusmods.com/skyrim/mods/86089/
Now the exchange want to give hacker a lesson and that's why they are offering a great prize for those who will tip-offs the hackers. Binance was able to safe all funds but they were not able to reverse all the trades that were made by the hacker that's why some traders had to bear the loss.
Binance want to punish hackers so that no one will again try to steal any money from the exchange for this purpose they have also reserved $10 mln so that if some thing like this happens in future they will be ready to pay to the informer. The amount that they are offering is enough to betray someone but there are very little chances that any one who had no involvement in the hacking know about the hackers.