It is conceivable Banks was making the joke at his own expense. But it did not sound like it. Rather, it was the sort of joke making light of your troubles that you tell to a confidant who can be trusted not to repeat it.
The remark was a telling indicator of Banks' "me against the world" state of mind after last week's release of the file covering the police investigation into large, supposedly anonymous donations to his campaign for the Auckland Super City mayoralty in 2010.
Banks maintained his Churchillian facade. There was no sign of contrition or meaningful apology.
In that context, his joke about fundraising was a conscious effort to retrieve a few crumbs of dignity in the face of what amounts to a humiliating and very public dressing-down.
But it was also a two-fingered salute to those disturbed by his seemingly cavalier regard for the laws on campaign donations.
He continued to shelter behind his claim that top police officers had essentially found nothing untoward in his behaviour, despite the file's incriminating contents.
These included a series of witness statements - most notably from managers and staff at SkyCity - which effectively make nonsense of the legal charade that enabled Banks to claim he did not know the source of donations to his campaign.
Other statements, particularly by Dotcom and his staff, cast Banks in a different, but just as awful, light.
His friendship with the internet tycoon is soap opera tinged with Shakespeare. Pick up the documents and you won't put them down until you have read every last one.
Things become truly tragic as Dotcom languishes in agony in a Mt Eden jail cell suffering convulsions and a bad back, with prison staff seemingly indifferent to his plight.
Dotcom's lawyer contacts Banks for help. But Banks does not want to know. After his release, Dotcom rings Banks, who says he is happy to see him. But he is in a meeting and will call him back. That is the last Dotcom ever hears from Banks.
At least it can be said that $50,000 bought Dotcom absolutely nothing by way of influence over Banks.
But that is about as good as it gets for Act's sole MP - and by implication for Act itself.
The latest revelations have made certain that his dream of retaining "Fortress Epsom" and using it as a platform for Act's regeneration is now pure fantasy.
Banks now has not a snowball's chance in hell of holding the seat. Although he insists otherwise, it consequently seems highly unlikely he will stand again in 2014.
Such has been the drain on his credibility that National voters in the seat are saying enough is enough. They will no longer comply with any nod-wink arrangement that requires they cast their electorate vote for the Act candidate for National's greater good.
With that kind of writing firmly affixed to the wall, it is not surprising there is speculation that some of Act's remaining best and brightest are now planning to form a new libertarian party of the right as a replacement.
John Key - conscious that another potential partner, Colin Craig's Conservative Party, may well fail to meet the threshold for winning seats - is meanwhile focusing ever more on how he might do business after the next election with the one politician and party with whom he has previously refused to be a partner - Winston Peters and New Zealand First.
For now, Key is lumbered with Banks by virtue of needing his vote to secure a majority on legislation where National does not have the backing of the Maori Party.
But this is now a one-sided relationship. Banks is now permanently indebted to Key for retaining him as a minister when by any reasonable test he has failed to meet the high ethical standards expected of someone in such a position.
Act's leverage - minute as it already was - has been heavily discounted accordingly.
Banks is now essentially an irrelevance. His only other options are to resign his ministerial warrant and go to Parliament's backbenches, where he could choose to vote against the Government on some measures - something which would lead to even more scorn being heaped upon him.
Alternatively, he could resign from Parliament. No one would bet against that happening.
But the more immediate question is how much damage Banks' remaining a minister is doing to Key's reputation.
Labour, for one, has quietly altered its tactics. It is focusing less on trying to destroy Banks - and with him Key's majority - and more on highlighting Key as no different from any other politician in terms of political game-playing.
For himself, Key is sticking to his line that he is taking Banks at his word that he complied with local body electoral law until it is proven that he didn't. Reading the police file would give more than enough such material for Key to change his mind. So he has not read it.
It is all a bit too convenient. So Labour is seeking to unpick Key's argument by forcing him to answer questions on the detail, such as what does he mean by the phrase "complying with the law".
Key has to be extremely careful with his answers as the Opposition will search for contradictions and then demand he explain. Once on the back foot on such issues, it is hard to get a quick turnaround
Labour knows from experience how distracting and wearingly this line of attack can be for a Government. But it is just as difficult for Opposition parties to maintain the momentum of such a line of attack.
When other opponents have been in trouble, Labour has promised to keep slugging away - only to ease off. This time, it says, will be different.
