Imagine, if you can, a time before cellphones. Remember the days when you went to the grocery store no one could get a hold of you? So if something happened, you might not hear about it for several hours. Now, times that by, say, 100 and you have the postal service during the American Civil War.
What we need to really understand here is that during Civil War, the United States was not one country but two. There were two armies, two ways of life, two forms of currency, two different everythings. So post Civil War, everything on the losing side was thrown into chaos.
To top it all off, the mailing system was dicey at best. Sending mail from battleground to battleground or even from the city to a battleground was not a reliable business. Buildings being set on fire and, with them, the paper records they contained made accounting and records incomplete.
In a nutshell: the soldiers didn't always get paid. And the confederate soldiers that did get paid may not have received money that was worth anything by the end of the war. They fought and risked their lives yet many of them had nothing to show for it. No money and possibly nowhere to live if their hometown got ransacked.
The Civil War basically created this population of desperate men and women. With nothing left for them at home, it's no wonder they were willing to brave the dangers of settling uncharted lands.