That's not FU money, that's enough money not to work for one year. At the end of the year, you cannot, in this context, say FU to anybody.
The recipe is simple. If you spend 50% of what you make, then you only have to work 50% of your life. If you spend 10% of what you make, then you only have to work 10% of your life.
Turn off all sources of marketing and watch your free time and savings swell.