Also would not agree the his opinion since there are men who can spend well their money. To many women spend excessively on things they don't need especially that online marketplace available they then to buy anything their wants and set aside their basic needs. That's why I disagree on this statement since see a lot of men doing some nice thing in terms of budgeting and they know how to handle their finances since they are the earner of their family.
Maybe he just see this on his circle that's why OP say this but if we talk about as a whole I think there's no difference between both since anyone is capable to be economical and its up for those people on how they handle their finances.
And for me personally, I look at it from another point of view, and I will not differentiate between genders in this case. Because it comes back to ourselves.
Maybe in this case, in some environments, women act as financial managers in the household, on that basis perhaps the OP sees women as more frugal than men.