Can a positive mindset really change reality, or not really?

We have now witnessed the ever-growing self-development, motivation, and mindset gurus & motivators in this era.
Although this is not necessarily a bad thing, I do often wonder, if positive mindset can really change one’s reality or hard life circumstances, or not so much?
for example, how about those people who, perhaps due to economic, social, family backgrounds, still have to work in cookie-cutter jobs, or doing those so-called boring, mundane, repetitive jobs such as in factory assembly line, office staffs, lifting heavy items/cargo, etc ?
and the saddest fact of life: how about those who live in third-world poor country such as Africa?
can one really ‘naively’ still think that positive mindset can & will change their desperate life circumstances?
or, all this positive-mindset thing is just a thing developed by the ‘spoiled’ advanced country & people with more haves in life?