This TorrentFreak article explains how Megaupload knew that it was mostly used for illegal purposes.

And this PDF instead tells the ups and downs of the founder of Megaupload. Bankruptcy, insider trading, fraud, money laundering, embezzlement, trafficking in stolen credit cards, mistaken identity, corruption, hacking NASA and Pentagon systems and much more.

In light of these facts, even if it sometimes was an "useful" website, in the end they deserved this ending...

Ps:

it seems that a site called Megaupload is still accessible at 109.236.83.66, but I do not have the absolute certainty that it is real; I think it's just a fake trying to make money with adverts

Using my rDNS tool you can see that this address belongs to a WorldStream customer, based in the Netherlands