Wholesaling/Flipping question that may have been asked

[Yeng Moua]

I, like many others have just started looking into the real estate market. I am currently reading up on wholesaling/flipping and wondering why investors don't just do a little research themselves and purchase the property of a willing seller? Rather, they wait until someone like me comes along and sets up a contract and then said investor purchases it from me and loses out on several thousand dollars? Could it be time? Manpower? Both? Other reasons?

I'm just a curious person with questions. This question has probably been asked many times over, but I'm new to this website and just learning to navigate and haven't found the question that I've posed. Thanks all!