I think you're modeling the wrinkles too intensely and not thinking about the actual material behind it. Refer to gravity, how are the folds coming down or what shape does it take when being worn by the head?
Also, look at references (or post them here). I found a hat that looked similar to yours but highlights the problems of too strong ridges.
Actually, learn to sculpt folds manually first so you understand flow. Once you are proficient, switch to marvelous. MD is never going to give you a 100% usable item...you need to be able to take that and go into zbrush to refine and add folds that work for your specific item. For your cap, have as much reference as possible...even if its not the exact same item, find front, side, back shots to get a good idea of how the folds flow into each other.
I think it's vital to learn to do them manually first. MD is a fantastic tool but there's no guarantee you will have access to it at every job and the best artists can do both.
Replies
Also, look at references (or post them here). I found a hat that looked similar to yours but highlights the problems of too strong ridges.
http://www.marvelousdesigner.com/
Figuring out how to do folds manually is still weird and hard for me to do.