Article with sources that goes into much more detail: web.archive.org/web/20230115112142/…/kim-dotcom/

Some hilarious highlights:

He bought stolen phone card account information from American hackers. After setting up premium toll chat lines in Hong Kong and in the Caribbean, he used a “war dialer” program to call the lines using the stolen card numbers—ringing up €61,000 in ill-gained profits.

In 1998, he was convicted of 11 counts of computer fraud, 10 counts of data espionage, and an assortment of other charges. He received a two-year suspended sentence—because, at just 20, he was declared “under age” at the time the crimes were committed.

In January 2001, LetsBuyIt was close to bankruptcy. Schmitz bought 375,000 euros in the company’s shares — and then announced he was preparing to invest an additional 50 million Euros. The news hit the market, and the stock price of LetsBuyIt surged. Schmitz cashed out, making a profit of €1.5 million.