You need to earn them. However, there is nothing preventing 100 alts being generated, you beating all of them and withdrawing $75.

Whats to stop you buying the $100 package; which also has a bonus of 640 coins for free. Then withdrawing them all and getting an extra $6.40?

You have to have earned them all. Fizzer won't let you withdraw coins that haven't circulated at least once.

There are coin-games for low amounts(10 coins) which a player cannot enter if his coin-stash exceed 1000 coins(so if you don't see them, send me your coins :D)
This is a very good design to keep some kind of balance between players,
by keeping the good seperated from the bad.
A good player will occasionally be eligible to play a 10-coin-game, but after making a high profit he/she will need to play games with higher stakes against, presumably, other good players.

edit:
Hence, making low amounts withdrawable would destroy this system.

Although possibly a "withdraw 5000 coins receive 40$"-option should be added.

Edited 8/1/2015 15:32:20

I believe Fizzer said the 75$ withdraw is temporary

I personally would like to see a Warlight shop and use my coins to buy a Warlight T-shirt hat or mug

+1 Ineffable