"There are always different people writing in. They might be a bit scared, or overconfident, or part of a couple where they think totally different things.
"Having real people there makes it that much more interesting to read it. These are real people, with their quirks and their own takes on things."
Holm says that enduring interest in the people behind money woes is why she's written her latest book, A Richer You: How to make the most of your money.
It features 184 of the most interesting letters she's received over the years, split into categories including saving, paying off debt and how to invest.
Holm is at pains to point out it's not just about money management. The stories she chose show how money opens up more options in life, giving people opportunities.
Then she laughs as she admits there's also a note of voyeurism.
"Being stories, it makes it quite an easy read, I think. They're compelling.
"I think people enjoy spying on someone else's money stuff, that we usually all keep so private.
"There's also a power in stories. You know, when you read a good novel you often learn something about human relationships.
"A good story will always be thought-provoking."
It's an approach that serves both her columns and the new book well.
But the solution can depend on so much; what a person wants, their values, the resources at their disposal.
Holm says talking about finance through people's stories shows not only the rules of the game but also when you need to break those rules.
Sometimes she receives letters from a couple in conflict, with different goals. Holm is asked to step in almost as marriage counsellor first and money mentor second.
Or there are people who have saved and invested until they're in a comfortable position. But they find old habits die hard and they can't bring themselves to relax and enjoy their money.
She finds that sad and tries to find tactful ways to tell them that life is for living.
On rare occasions someone's story keeps her awake at night.
Such as the woman whose husband told her she wasn't good with money, as she spent too much. So he gave her an allowance and handled the rest of it himself.
The woman became unhappy in the marriage but felt stuck. She didn't know how much money they had, where it was - or how she would cope by herself.
"I'm haunted by that conversation. I hate that, I hate hearing that.
"It's your whole life we're talking about here."
Holm says that's one reason why she works to write her books and columns in plain language.
Her biggest worry is that the people who need her advice most will never hear it, because they've given up on ever being able to manage their money.
But she says she's yet to come across a situation where she can't offer some type of help, even if it's directing them to free, independent organisations such as the FMA or Money Talks.
"People don't know how much free, unbiased advice is out there, places where they can get help.
"I'm certainly not afraid of saying, 'The Government should change that,' if there's something the Government could do. Then getting comment from politicians on, 'Why aren't you doing this?'"
One of the newer changes she's noticed in her career is the influence of the internet.
A recent example came in the rise of GameStop and other "meme stocks". Prices soared on the basis of chatter online, particularly Reddit message boards.
Part of the trend was a desire to stick it to the establishment hedge funds. But another part was simply a level of hype that has come alongside a renewed interest in the sharemarket.
Holm says she, for the most part, is glad to see people taking more interest in shares and investing.
But some of the message board hype reminds her of the shares clubs in the 80s and the way interest reached a fever pitch among new investors.
"In the 80s everyone was going mad for shares, everyone was in share clubs. You know, getting together every Wednesday and deciding what they were going to buy.
"It was fun but the markets went mad and, sadly, a lot of people borrowed to invest. So when the crash came many people got hurt. That put many people off shares until the last few years."
Holm says she doesn't want anyone to think she's warning against shares investing, but she does have a word of caution for those at the "extreme" end.
While the online chatter pushed GameStop stocks to vast heights, it then abruptly plunged back downwards.
Rather than sticking it to the hedge funds, it was smaller investors who were burned in the biggest numbers.
"Obviously the Internet made a difference to everything we do in life but it is getting a little bit worrying.
"It's the same type of people who are feeling like they can't lose with shares, thinking they've worked out how to play the sharemarket, especially if they've won two or three times.
"When people start borrowing is when I start to get worried. That is what happened in the 80s a lot and very suddenly people got in too deep.
"Then I'm standing there, being incredibly boring, saying, 'You shouldn't put money into shares unless you're not planning to spend it for 10 years.' And you know that people with GameStop and things like that, they're talking about even what will happen in the next hour."
Asked if there's one thing everyone should do, Holm instead opts for two: one to do and one to avoid.
The first is a strong recommendation to join KiwiSaver and take advantage of perks, including Government and employer contributions.
Even those who are retired should consider KiwiSaver, she says.
"I still think a lot of people over 65 don't realise that they can join.
"They're well-regulated, and tend to have lower fees than other funds.
"I would encourage everybody to think about how they could make KiwiSaver work for them. There isn't a person, really, who can't benefit."
Next is to avoid high-interest debt, through the likes of credit cards and car payments.
"It's so insidious, the way that high-interest debt just eats into people's savings.
"If anyone is struggling with that, go to Money Talks, the website. You can get a free financial mentor, they're trained to help you get out of debt. They can even help you negotiate with the credit card company to reduce your debt.
"They can help you to get this terrible monkey off your back. It must be such a relief for people when that happens."
Holm's short-term goal though? To get in her evening swim before dinner. She lives by the sea and tries to get in a beach visit as often as she can.
After all, life isn't about the money. It's about the life you can create with that money.
A Richer You: How to make the most of your money, by Mary Holm (HarperCollins NZ, $37) is in book stores from March 15.
Money Talks is at moneytalks.co.nz