That's not intelligence, it's privilege and having sufficient disposable income to invest in cost saving.

Items like chest freezers that cost more electricity to run, but allow me to buy more food and freeze it. At the cost of larger electricity bills.

It's having enough money for fuel so I can drive 80km to Costco.

It's having /time/ so I can just do the baths of all the above because I'm not working 60 hour weeks to feed the family.

That’s grade school arithmetic. We’re not talking about people who aren’t intelligent enough to do arithmetic, we’re talking about people who don’t have the correct mindset and motivation to make small, incremental investments in their future.