Why Dr Karl is working harder than ever, with a new book on the way at 72

"Dr Karl" Kruszelnicki has four degrees, has written 46 books and, at 72, is working harder than ever.

Previous careers included producing some of the first MTV videos in Australia, setting up the first cable TV channel and being an engineer, roadie and TV weatherman.

He spent 28 years in formal education and now works at The University of Sydney in the physics department as a "science populariser". His latest book, Dr Karl's Surfing Safari Through Science, is due later this year.

What was your first job?

It was working as a labourer at the water board at 16 years old - that was such a good education. I didn't know how to use a shovel and there were so many things they taught us. One guy gave me a great lesson: "Karl, you're different from me, all I can ever do is dig ditches, you can do anything you want. Me, I can't." I've never forgotten that. Always have compassion for people who can't do what you can do.

What's the best money advice you've received?
Read the fine print. Try and save a bit. Trying to predict the future is hopeless. I was bemoaning I didn't buy Bitcoin at 1.25 cents each. Even hedge fund people can't predict the future.

What's the best investment decision you've made?

Filling my brain and paying for my kids' education to the end of university to give them a clean start - because they're the future.

What's the worst decision?

When I've let my emotions get in the way of a clear financial decision and that happened as a result of me not yet having read the words from The Godfather: "It's not personal, it's strictly business."

I've gone into partnerships with people and let my emotions run the financial side and that was wrong - almost as wrong as not buying Bitcoin.

What is your favourite thing to splurge on?

Family - anything to make the family run better. The one thing I realise as a medical doctor is that I've been with people near death. No one ever said "I wish I'd worked harder" but instead "I wish I'd spent more time with family", so I figure I may as well do it before I die.

If you had $10,000 where would you invest it?

I'd probably follow the advice of the hedge fund people and I think they're going fairly short on equities, but I'm not an expert. I'd follow the people who are the experts, and the hedge funds are in the long term and that's my rationale for following them.

What would you do if you had only $50 left in the bank?

Absolutely nothing. I'd make sure I had it in cash and see how long I could stretch it. If you blow it all too soon, and turns out you could have done better by hanging on a little bit, you're screwed. In my father's case, he managed to hang onto a tin of sardines and it saved his life to use as a bribe to swap his identity and escape from a concentration camp.

Do you intend to leave an inheritance?

Yes, we do. Children are a good investment in the future and they can make the world a better place and I want to help them.

What are you most proud of in your career?

Reducing the number of babies that died unnecessarily from diseases they could be vaccinated against. I'm proud of the fact I've been pushing the pro-vax line for a long time. I was working as a doctor at the Children's Hospital at Camperdown when I saw a child die of whooping cough. At that stage we'd had zero deaths from whooping cough in all of Australia but A Current Affair was pushing the anti-vax line, and when I spoke to the parents of the child who died they said A Current Affair told them you didn't have to get vaccinated. I've had many people say they were swinging on the idea of vaccination, but thanks to me they got their kids vaccinated, and there have been fewer dead babies.

What has been the best money-making career move for you?

Accidentally getting a degree in physics and maths. It's a great mental toolbox. When someone says something like "I have this tea that will cure syphilis, etc" you know to say, "Where's the proof?" Then engineering was good because you get to disturb the universe and can manipulate the universe to be what you want. Medicine was good because I knew how the universe was made but I had no idea how the body worked. Getting a broad education was the best thing I did.

Finish this sentence: money makes ...

... the world go around and for me it's an incredibly essential part of the package.

Get stories like this in our newsletters.