800k can support a 24-32k a year lifestyle for 30ish years (indexed for inflation). This of course, depends on the timing of the ups and downs of the stock and bond markets, or what ever investment you choose. A really bad sequence of years could have you running out of money in 20 years. A really good sequence will last you more than the rest of your life.
There are some areas of the world where 24-30k is fantastic. There are some areas of the US where 24-30k a year is ok. There are some areas where you just can't make it on that amount (just about any large city, coastal California).
If you just put the money in the back and withdraw 30k a year, you'll run out in around 26 years. But in 20 years that 30K won't seem so good.
A better plan is to find a job you enjoy (it does not have to be your passion, you just need to enjoy it). Become really good at it. Keep a balanced, healthy lifestyle, and don't retire until you are good and old. People who stay engaged, who continue to work, who have no money stress and acceptable work stress tend to live longer and enjoy life more.