Life is not a game of improvement, but rather a game of tradeoffs

Most people think life is like a linear line that keeps going up as time passes, maybe there's a point when we're younger, as a child everything we learn grows tremendously and our abilities grow rapidly every year, yet once we're grown up we have reached a stable point and have mastered a skill / expertise in a particular field, life is no longer about improvement, but about sacrifice / exchange of time.