I don't get it myself but some people either can't do or don't want to do it. If i was paying rent on my current house it would be 1200 per month but a mortgage is 800 and i will be able to sell it at any time.
I know that a lot of my friends put more money into disposable things rather than lasting items like investments or houses but they will be in the same place ten years form now. Living paycheck to paycheck as they haven't any other forms of income coming in. Just constant bills.
Small changes now will pay off long term.