When a contract expires you can no longer execute that contract.
@Bill Gulley gave an example of you purchasing a primary residence and then that person having to get a motel and eat out every day. You can avoid that scenario by not purchasing primary residences if you aren't willing to take that level of risk. Simply start out by wholesaling a run-down vacant house and doing the owner a favor.
There's risk with everything you do in life, the more risk = the more reward. If you don't wholesale the houses in your target neighborhood, someone else will.
You should know the basics of real estate before you jump in, but don't go into information overload trying to read 15 books before you do your first deal. Your true education will come from applying what you know into action. All you need to know how to do is the first step. Perform the first step and then study/post on biggerpockets/find a local mentor on how to do step 2.
Step #1 for you would be to locate a target neighborhood and try to find distressed owners. Go talk to people, knock on doors, send direct mail, put out bandit signs. Take Action. Inaction will get you what you currently have. The only way to be successful is to take the first step.
If you want to take the lowest risk form, simply bird dog for a wholesaler in your area.