well if you marry a billionaire & make sure he draws up in his will that he leaves his entire fortune to you then god forbid passes away then you can retire at 30!
another is if you simply played lotto or gambled and won billions then invested properly then at way you also could retire!
last but not least if you bought a property, and it was yours legally & digged an x amount underground just to find a large sum of oil or water then you would be rich & able to retire as well at 30!
Then again, if you are super smart & happen to be a whiz in computers & know programming, you can create something amazing like a start up business & sell it for billions as well! Either way you need skill, knowledge, money invested or an investor...and there you have it...just some ideas on the top of my head.
I know cops can retire at about 42 and that's because of the retirement program that they are offered, forgot which one it was.. If you have something like 401k, DBP (Defined Benifits Plan), IRA, Roth IRA, or 403-b then you're set up to retire anywhere from 59 or higher, typically.
These plans are all pretty good as they are privatized and basically, you're in charge of them.
But realistically, I highly doubt you can retire at 30 unless, as mentioned, you're Bill Gates.
Assuming you are 30 and you'll live until you're 80...
To have $40,000 a year (not much) to live on, you would need to have $633,724
To have a comfortable life with $75,000 a year, you would need a little over a million dollars.
Some things may vary, like whether or not your house is paid off, what kind of loans/bills you have a month and how much interest your money earns in the bank. Good luck...
You'd need to be Bill Gates, just about.