Let's assume Parker's money management and financial advice will be, well, on the money. But his upcoming payday (if all the talk of a done deal is correct) triggers another question - win or lose against Joshua, will the hunger remain? Will the urge to compete at the highest level be there once a life-changing sum, as $12m still is, is earned?
There have been plenty of New Zealand athletes for whom the prize was just getting to, for example, a Commonwealth Games or an Olympics. There is no disgrace in that, far from it, but modern sports management and professional training methods means such amateur concepts are largely gone these days.
When he fights Joshua, Parker will be 26 - young enough to come again should he lose; he is lucky in that the heavyweight division is more interesting than it has been for many years with Joshua, American WBC champion Deontay Wilder, the returning Tyson Fury and supporting players such as Russia's Alexander Povetkin, Cuba's Luis Ortiz and Bulgaria's Kubrat Pulev all hot to trot. So a loss to Joshua need not damage his career beyond repair. Win, and he will have four belts and a parade of mandatory challenges to deal with.
The prevailing international view of Parker is that he is a second echelon champ - good, but not good enough to threaten the potential Joshua dynasty.
That may play to Parker's future advantage, should he lose to Joshua, as many seeking to dethrone the champ would look to measure themselves against him.
Joshua is a mighty, chiselled, boxer who stands 1.98m and weighs over 113kg with punching power and - his greatest weapon - a reach of 2.08m or, in boxing's undecimalised language, almost 7 feet of reach.
That means he can lay a glove on you from about 7 feet away - and not just a glove.
He has hands like plates; one of the British newspapers, carried away as they often are when confronted with sporting hope, said being hit by Joshua's 14-inch clenched fist (think about it) was like "being whacked by an 11lb sledgehammer travelling at 30mph".
Quite how anyone would know such a thing is beyond reason but it underlines Joshua's power.
Yet a good defence and clever movement can throw off even the biggest puncher. The rippling muscles can become a burden if a fight drags on, just as the heavy armour of the knights of old became a hindrance if they did not make a quick kill.
That may be partly why Duco boss David Higgins, even as he seeks to tie up the Joshua fight deal, continues to goad the Joshua camp with insults like "glass goose" , referring to Joshua's supposed glass jaw.
Parker's best hope may be if Joshua comes out steaming and punches himself out. It could be Joshua's only weakness (though some say he is often slow and robotic). Although Parker has not shown much of it in recent fights, he has the ability to throw fast combinations (boxing's most attractive and telling weapon) and to move where the opponent's punches are not.
It - and he - are a long shot but boxing is full of long shots who beat the odds. Maybe the best simile is Evander Holyfield, an even smaller heavyweight than Parker but one whose win record includes giants such as George Foreman, Riddick Bowe, Buster Douglas and Larry Holmes, and a shorter but dynamic champion in Tyson. Holyfield drew with Lewis before Lewis won the rematch eight months later in a fight some thought Holyfield won.
Parker has nowhere near the record nor the cachet of Holyfield, the only four-time heavyweight world champion. But he has a good chin, a good brain and is a genuinely gutsy character. He has a boxer's chance against Joshua. He also has a chance to keep fighting at the top of the division, if he wants, even if he loses to Joshua and there is no rematch clause.
That's if $12m doesn't get in the way.