I take no credit for this .. did some research on the net to find a faster way to get the "Billion Dollar Babies" achievement and I found this method a stupid fast to make cash!!
Get to the chopper pilot PMC and start the Winch Challenge
AAAYYEE! GET IN THA CHOPPER!! NAOW!!! ^_^
Drop the winch down
Latch onto the toolbox
Keep the toolbox centered or at least within the circle goal
Fly straight up and keep climbing
While you climbing upward, (1st important part) release the toolbox at about 275ft high then (2nd important part) Immediately fly to the right and keep flying to the right
* Remember release the winch while you are climbing or the winch will catch the toolbox mid-air and will be "out of bound" unless you align the toolbox and the circle goal once again.
Wait about 2 - 3 seconds later while the toolbox is falling toward the goal circle .. then you will win the wager
The entire thing shouldnt take more than 2 minutes to win this bet
Rinse and repeat this for about 45 mins and you will have a billion dollars and your achievement
Notice that the chopper pilot PMC bet will be higher than your max bet of 5 million after you do a few of these .. just dont mess with the wager
But as for me, the achievement is glitched I cant unlock the achievement even though I have a billion freaking bucks! Hopefully I will be able to get it soon.
Otherwise, GOOD LUCK!
Update #1 - After a few hours, when I started up my X360 with Merc2 in .. I got the achievement. The world is okay now. Game on!!