Economics in college, why is it required?

Why do they require that you take Micro and Macro Economics for the majority of majors offered at universities?

I am a Construction Student, when will I ever need to figure out the marginal propensity to consume?

Depends on the degree you're getting & where you're getting it. I took economics (macro / micro combined) but it was for my business minor...otherwise, I wouldn't have had to take it.

Though in construction, if you ever wanted to be the boss & run the business as opposed to working for another as a lower level employee, then some of the economic fundamentals will definitely come in handy. Or even if you make management, etc.

'economies of scale' for example, why most industries tend towards oliogarchy, that's one that I've never forgotten & is useful in life in general.

Also, the studies on opportunity cost, 'utils' as a fictional measure of satisfaction, etc, are all good basic business practices that are broadly applicable, in my opinion...and it's been a decade since I took the class but I can still recall a few of the lectures.