The other thing missing is you need to live somewhere now. You also have other considerations - if you are starting a family you typically will need to have a place for the family to live and that forces you to buy now. This is why most deflation arguments fail - people need to live, so they will buy food, and shelter (including clothing). People will replace their broken down car. People will buy toys if they can afford it.
Even if you can buy the house for $200k next year, you don't know that the price will go down - I've seen prices go down and then go back up more than once in my life. Maybe you get unlucky, but maybe you bought the bottom, you have no idea what inflation/deflation will do in 5 years and only educated guesses for next year.