Bankroll? - Just Gotta' Know

Okay, I've been reading this board for awhile now, and many, many times have seen posters saying you need to have $15,000, $20,000 or even $30,000 in your bankroll to be betting a $25 to $200 spread.

Now honestly, how many people have that kind of money to begin with?!?
If a person REALLY has that kind of cash in an account, then perhaps you should play in the " world's largest casino" - the stock market!

My question is, must you really have that kind of $$$? Is there wrong with a $5000 - $6000 bankroll and bet $25-$100?

Thanks!