"NS&I Premium Bonds are a savings account you can put money into (and take out when you want), where the interest paid is decided by a monthly prize draw," Martin recently explained on MoneySavingExpert (MSE).
"You buy £1 bonds and each has an equal chance of winning, so the more you buy, the more your chances improve."
Premium Bonds customers can invest between £25 and £50,000, and prizes that get shared out range from £25 to £1 million.
Although the distribution of prizes changes each month, since 2014 there have been two monthly £1 million jackpot winners - the prizes are tax-free.
However, posting on X, the MSE founder revealed: "Why do so many people give children Premium Bonds? Premium Bonds are only a decent bet if:
"Most kids have/do neither. With £1,000 in over a year with typical (median average) luck you'll win nothing."
But some Premium Bond holders seemed to disagree with Martin, as one responded: "Completely disagree. We've had returns that easily outstrip interest rates. Maybe we're just lucky."
Another replied: "Statistically, I've done a lot better with premium bonds than anything else - especially during lockdown when interest rates were practically nothing."
In November, NS&I announced the prize fund rate for Premium Bonds will become less generous from the January 2025 draw.
It will reduce to 4%, down from 4.15%, the Treasury-backed savings giant said.
The prize fund rate for Premium Bonds was cut to 4.15% in December, down from 4.4%, according to an earlier announcement.
The odds of winning in January will remain the same as in December - at 22,000 to one.
The changes include an estimated 82 prizes of £100,000 in January, down from 83 in December.
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There will be an estimated 166 prizes of £50,000 in January, down from 167 in December.
The estimated number of £1 million prizes will remain the same, at two.
There will be a higher number of lower-value prizes of £25 in January, estimated at 1,815,854, up from 1,509,458 in December.