you do not have a good plan that's why 不明白每月6千纯收入为什么不能退休

If you read Yahoo finance that post on 10/13/2016, most retired people spend 75% on Social Security pay check on health problem.  

I calculate that even you paid off mortgage, cars, you still need to pay property tax (depended where you live and value of the house), insurances, utitlities, car, house maintainace/repair, and etc.  The most expensive parts that you did not include long term care.  If you cannot be independ live along, you need to hire someone to take care of you that most cost a lot.  Nurcing home as $7000/month.