I mean engineering salaries as decent at best, yet they take a lot more work than it's worth. Why not become a dentist and make 300,000$ yearly? Or study business and make 100k+.

What is the reason?

Because engineering is prestigious/looked well upon in a lot of countries (probably the main reason). Lack of language skills is less of a barrier for engineering compared to a lot of other majors. Engineering is a lot more mobile across boarders than some things like dentistry (think of accreditation, licensing, etc sometimes can be a hassle).

Regardless, a lot of international do in fact go into dentistry, business, etc. You wont find a lot of sociology though..

You talk about "engineering" as beeing just one career; actually, as you know, "engineering" offers you a huge range of possibilities and specializations that you can't find easily in other careers. I have studied 2 years of dentistry in my country, very well payed (may be the best income earning career).. but money doesn't matters to me if I'll do something that I don't like the rest of my life.

And we have to be honest, engineering programs in Canada are very atractive for international students, they offer tons of possibilities that doesn't exist in other countries (at least in mine).

They don't?

But, I suppose the benefit of engineering is its supposed job security (which even recently is wavering quite a bit).

I don't think of it as particularly 'sad'. Physicians have different roles and skillets compared to engineers, and you need both of them(at least) to cure a patient.

It's also a choice. Some people don't really enjoy biology. Some people can't wrap their heads around principles of Physics.