21 Bitcoins in 21 years seems like the perfect way to go. Anything less than 21 Bitcoin just doesn't feel right, you gotta hit that magic number to be safe for a fantastic early retirement, until then, I will not rest for a minute, every second must be about thinking how to increase your Bitcoin stack, otherwise you are wasting your time.
Very true, we should engage ourselves in earning bitcoins at a moment, as it will be more worth in future, more you hold, more profit you earn, and better retired life you live.