design your life for the future, don't just think about eating or buying snacks today.
Good point. Delayed gratification will lead us to better paths of our life. It might be difficult for now but soon you will realize that all of it was worth it and it will even bring you more benefits in the future even if you suffer for a little bit right now.
I invest like 80% of my salary for many years, technically I can retire now because 4% of my investment is enough to cover my annual expenses. But, no one knows if I get sick in the future, my wife turn to be materialistic woman, school fees rise really high than 4% annually etc.
This is why there should be savings for different kinds of things. Health insurance can save you inn cases like that. As per school fees, you are right that you can't truly retire yet until one of your kids graduate and have a job of their own because until then you do not know what can happen or what will your kid be doing. Life is difficult and early retirement is a dream that is very difficult to achieve.