If you invest $1,000 when your 18, I read somewhere where it could be like half your retirement when your 65
I suppose it's possible. But then why isn't everyone doing it?
If you want to retire on $50,000 a year, assuming a defined contribution pension setup, you probably want to save at least $1,000,000 before you retire. That number is pretty simple and ignores factors like inflation, longer life expectancy etc. It won't buy you a brilliant annuity either, so don't expect a pension for your spouse when you die.
To get half of the money towards that then you need to get around a 16.8% return each year for 40 years. I'm sure that's physically possible if you invest in the right things. Chances are, you probably won't though.
Anyway, my advice is to enjoy your money for now. You are young enough to not have to worry too much about saving for your retirement. Though $1 invested at 18 is worth more than $1 invested at 64 when you come to retire!