You never reach 100% freedom and security. You only approach it asymptotically as you gain more money. So maybe for some, their threshold for "enough" is higher than you think. Maybe for someone else, they just haven't figured out what to do with the freedom yet, so they keep going and moving marginally closer to that 100% so they can better enjoy it when they do know what to do with it.
You can't buy time. And a demanding job that'll get you that 20k/month will start to degrade your health at some point, rather sooner than later. And in most of the world even 'only' 1/4 of that will make sure you're living a quality life, esp if you can earn it with part time work while spending extra free time exactly how you want to.
But hey, people finding happiness in owning more than they can spend or use are free to work as much as they possibly can.
No idea why so many people always aim for more money instead of more freedom