I really wish articles written about studies like this, where all they found was a association between stuff, and not a causal relationship, would explicitly say so. Perhaps through a little box near the end of the article stating, in simple terms, "the authors found that X and Y are associated. This does not necessarily mean that doing X will cause Y"
I know the people who read the actual study in journal, entitled "Optimism is associated with ...", will notice the word "associated" and know what to make of the results. But Im pretty sure a good number of people who read pop-science articles like this dont know that "correlation doesnt imply causation". They will come to the wrong conclusion, and we cant blame them! Ive found this to be true in friends and family.
From https://devdegree.ca/pages/student-experience. It appears that you dont get paid 40k. 40k per year is the total they will expend on you, with tuition being part of that.