First year interest on that mortgage amounts to $11,250.00. The credit card interest equals $3,800 in the first year. 

A mortgage taken out today will average a 6% interest rate over 20 years, based on historical data. Over 20 years you will pay over $350,000 in mortgage interest on that $500,000 mortgage if you don't make additional payments on it.

Then we have the basic issue of investing extra income or paying down the mortgage.

So here I am with a $500,000 mortgage, do I put the $10,000 of extra income I have each year into investments which might yield me 5% ($500 return). Or do I put it on the mortgage and save myself many tens of thousands in future mortgage interest payments?

As I stated everyone who looks at this issue gets caught in self deception. They never bother to look at the big picture of compounding interest.  A mortgage today may have a low interest rate but compounded over time those interest payments dwarf interest paid on all other debts.