Do you go into retirement at 19 years old?
Depending on what your wallet is worth today, that wouldn't be a very smart move in the U.S.
How do you cash out?
Very carefully.
Do you take the capital gains hit, in exchange for USD so you can make tangible investments so you never have to work ever again?
Only on as much of it as I need.
Would IRS still rape you even if you tool the capital gains hit?
Of course.
I trade BTC as an investment only...and eventually wish to convert back to USD so I can diversify my portfolio.
You may regret that if bitcoin reaches widespread mainstream use.