That's simple, specifically the revelation of his wealth source, namely the large-scale copyright theft of Hollywood movies, which has led to the extradition order by the FBI. Due to preposterously idiotic police behaviour, who instead of knocking on his door and handing Dotcom a summons, mounted a scandalously infantile raid by 76 armed police and two helicopters. They then wrongly threw him into prison, so understandably the public reaction became sympathetic, more so when it was revealed he had been illegally spied on by the GCSB clowns.
Dotcom's loveable maverick reputation collapsed, despite his vigorous legal efforts to prevent it, once details of the FBI's claim became public. Hitherto he had presented his business as that of an innocent bystander, akin to a taxi-driver delivering a passenger to a bank, then subsequently being charged with aiding and abetting a crime after it was found his fare had robbed the bank. But the FBI claims he had the means to control his Megaupload site's content, but far from doing so, actively incentivised the placement of movies on his site.
In rebuttal, Dotcom points to the terms service users were obliged to agree to, which included an undertaking not to post copyrighted material. He further argues that the sheer volume of material was such as to prevent practical policing.
The user copyright undertaking won't wash in any court and he knows it. It was his primary income source arising from many tens of thousands of downloading users exploiting his site's stolen movies, but Dotcom, the site owner, implausibly claims this was all unknown to him. Anyone wrongly charged with a serious crime should be ultra-eager to get into a court and argue their innocence. Instead he's wasted millions trying to avoid doing so.
So he has resorted to a final desperation measure, namely to spend millions attempting to buy a change of government which he hopes will over-ride a court-backed extradition order, an inevitable outcome once he's used up all of his legal ploys.
He's wasting his money as no government will do that, regardless of any undertakings from the soul-selling abysmal no-hopers he has garnered together to fund as a political party. If anything, his efforts will hugely harm the Opposition cause in Balkanising and confusing its message, thus presenting an electoral option with on one side, a rabble of dissimilar, mutually antagonistic parties, all with unpopular leaders and wildly different messages, set against a stable governing party with the most popular leader in our history.
This is the fifth party Dotcom's new leader Laila Harre has belonged to which speaks volumes. Harre will always be remembered for the funniest political gaffe in our history when she explained her 2002 defeat by lamenting on TV that voters had voted with their heads rather than their hearts. If she wants hearts then far better she assists Minto with a one-man black and white minstrel act which will pull the punters in droves, but when it comes to heads, like Dotcom, she's history.