I like to use descriptors traditionally used for food to describe every day, non-food related topics, and this one is no different. FU money is delicious. It's like mashed potatoes and gravy, or those slightly burnt (only slightly!) portions of pie crust. It may not be gourmet, but it's comfort food to the max.
FU Money means you can effectively put a stop to full-time income immediately and still remain financially independent, at least for a while. It doesn't necessarily mean or imply that you can flat out retire. But, it does give us options, and lots of 'em! FU money is good money.
F ME, money is not good money. It means that money controls your life. It probably means that you are living paycheck-to-paycheck and beholden to a full-time job in order to maintain your lifestyle.
The large majority of us start out with F ME money. As youngsters fresh out of high school or college, we begin our accumulation phase without a lot of money and, thus, we are forced into the position of required full-time work even if we think our boss is a prick. We can find other work, but our ability to rage-quit by spitting obscenities as we gracefully walk out the door to the envy of our co-workers like a superhero isn't quite there yet.
And that's okay. We all start somewhere. To retire early, we can't let our money screw us over.