Strange as it sounds, you can also borrow to save. In fact, he told his son Barney to do exactly that. He slowly reduces the loan balance with the income he earns on the investments, and tops it up with his own savings. Over time his debt goes up and down and his assets go up and up. As long as the borrowing is conservative, it shouldn't be risky.
Many advisers recommend instalment gearing - borrowing in small parcels, or instalments.
This can make you a millionaire. Even so a more conservative saving regime is often the most successful. A lot of people set unrealistic expectations, which is often why they unwind their savings plan early. But it slowly adds up over time. As his salary increases over the years he intends to keep adding to his monthly contributions.