Because a decent engineer has a higher ceiling for income, that's why.

Eight years? Only four years to get an engineering degree.

I've learned not to debate this topic, good luck in whatever decision you make.

From the productivity of the borrowers inside the economy of the island.

Currency is a medium of exchange for goods and services and the total amount of money available increases in a growing economy.

EDIT

Thinking about this more, I get the sense that a lot of folks don't understand what money is and how it's created.

Let's take two people. One fixes pinball machines and the other has a cow that produces milk. Let's say you agree to fix my pinball machine in exchange for five gallons of milk that my cow produces.

So, you fix it. I owe you five gallons of milk. Except the cow hasn't produced it yet. So I give you five tokens, each one worth one gallon of milk.

You take them. But instead of coming back next week for the milk, you exchange one token each with five different people who agree to take one token each for various pinball parts. And they each cash them in with me later for the gallons of milk I owe.

Those tokens had no value until we agreed on what they were worth. They became money where none existed before. They became the medium of exchange of goods, services, and productivity.