This is a simple theory which I believe most people who ever wondered about the subject would have figured out.
Why does it seem like every High Ranking Marine has a Devil Fruit?
![](https://www.opfanpage.com/wp-content/uploads/2020/08/03ff45400f50a2596b5626b15e64f09df901381b_hq.jpg)
I believe this points to the theory that the World Government has a vault with Devil Fruits in it.
![](https://www.opfanpage.com/wp-content/uploads/2020/08/usil057ry4fy.jpg)
Whenever a Marine proves themselves and does something that helps the Marines as a whole greatly such as maybe arresting or killing a large number of pirates either over their career or in one battle, or saving the life of someone important they are given a promotion and a Devil Fruit.
This is why Marines have Devil Fruit powers, especially the Admirals.
![](https://www.opfanpage.com/wp-content/uploads/2020/08/Isshos_Devil_Fruit_Ability-1-1024x577.png)
This is further proven by CP9 when 2 members of the group were given Devil Fruits as rewards for their work.
![](https://www.opfanpage.com/wp-content/uploads/2020/08/maxresdefault-51-1-1024x576.jpg)
There are a few exceptions like Monkey D. Garp but I would say that is, more or less, just them refusing it.
![](https://www.opfanpage.com/wp-content/uploads/2021/07/d052f4624c142f6d9e4cf269bf29cec5-1-1024x539.jpg)
*Theory by Sniper king ussop