you can retire easily if you are very good at management. But it requires a lot of efforts, hardwork and devotion to your work not everyone can do that.
I think it's same to sole extent that you sacrifice your wishes at young age and it will benefit you at old age or you enjoy your young age and then you'll suffer a bit at the old age. By both techniques you will suffer a little and now you have to choose which part of your life you want to sacrifice a little.
Devotion to work? If so, then we will never retire early. What we truly need here is confidence and planning. The traits that you said are still important and we must do them when we are still working or have resigned already because our saved money that is allocated for retirement can run out, so we still need to have another source of income but it may not be demanding anymore as our previous jobs. It's hard to sacrifice but it's needed.
I still think there are exceptions to this like on your example. For me, I'll never sacrifice my childhood because I can only regret it later on. Same goes when I'm old and choose to work longer because I won't still enjoy my money later on.