So by this time next year a couple thousand of those 4 million will be dead.
"Couple thousand"? By your own numbers we should expect around 360 murders (48/100,000*750,000), most of which will not occur anywhere near where most people actually go. Tens of thousands work downtown and Ford Field, Comerica Park, Joe Louis Arena, Detroit Institute of Art, Cobo Hall, Wayne State University, several casinos and quite a few other attractions are downtown. Few people ever have a problem. Get a clue.
There's a lot more to avoid in Detroit than the snow.
Why would I want to avoid either Detroit or the snow? Literally millions of people go to Detroit every year without any incident whatsoever. Most of Detroit City is no more dangerous than any other major metro area in the US. An most people DON'T LIVE IN DETROIT CITY.
Plus I like to ski and skate. Why would I avoid the snow?