I would like to semi-retire on my hunting land and open a perennial nursery, as I enjoy plants. Taxes and insurance are about 1k each a year for the property. I have a 350k mortgage for 68 acres agricultural and wetland. I use the land for perennials, timber, and hunting.
At an average 10% return, in 10 years the expected value of the fund will somewhere around $1.4 Million. In 20 years the expected value will be somewhere around $3.7 Million. From there, you could get to a safer return of 5%, which would give you an income of $185,000 per year. I would hope you could live off of that for the rest of your life.
Other than that, what do you want to do? Do you want to get a master's degree and improve your knowledge and income? Great! you have more than enough money to afford to get a degree, and with a higher income you could probably even contribute MORE to your "retirement" fund.
You can do whatever you want at this point. The only risk is that you do something foolish (like blow it on cars and boats, or use it ALL to start a new business that then fails), but you certainly have the ability to do whatever you want.