Yeah, well... it would be nice to win the lottery, too!
While all of the above are desirable, none are essential to the creation of a first-rate, page-turning mystery novel. Thousands of people have read my three Julie O'Hara murder mysteries about a body language expert who "sees" what people don't say, and I never went to college or set pen to paper until I was sixty-five years old. A voracious reader, one day I closed a favorite mystery/thriller and thought... I could write one of these.
What is essential, then?
1. A broad love of literature, especially for a particular genre.
2. A willingness to study hard and long, to absorb the insights and advice of successful writers of that genre and apply them.
3. A strong work ethic that will keep you writing, week after week, month after month, until your story is told.
4. A sense of pride that won't let you put it "out there" until you polish it to near perfection, and then finally let it fly because nothing, after all, is perfect.
There's no better time than now to indulge your creativity. With the advent of e-books, you don't need an agent or a publisher, so, if you've always wanted to write a mystery, go for it!
Remember, Agatha Christie didn't go to college, either...