yaff80 — Your calculations are not taking into account the down payment. Although it is true that when you rent you are “throwing away” that money, a big portion of those payments, especially in the beginning are to pay interest on your loan, which is also money thrown away.
On the flip side, you are tying up your down payment, which could theoretically been invested in such a way to make more money than the appreciation on your house. As many others said, this is a very individual financial question. For example, here in Israel banks require down payments of about 35%, so obviously that is a bigger factor than in the US where even with “tighter standards” you can easily put less than 10% down with good credit.
Also there are often additional expenses that come with homeownership, such as property taxes, which must be factored in. The market conditions and interest rates were already mentioned (in recent years many homes lost significant value). Tax benefits are also very individual. The benefits of deducting interest payments will vary depending on your income, size of your family, etc.
I’m not an accountant or financial planner, but I can definitely create scenarios in which it would not “certainly make more sense financially to buy.” Of course there are many psychological advantages to owning a home, but we are talking about the pure finances of it
Grandmaster — why don’t you ask your professor what cases he is referring to?