I bought my Ball from a family that bought it for their kid. Their kid quickly lost interest so they sold it. I think many times people buy a snake for the cool factor and think it is going to be something more than it is. They buy it and then realize they bought a pet rock that likes to hide most of the time during regular human hours.
So as long as you do not mind a pet that is not excited to see you and hides from you most of the time you should be alright.
Second I think people get into it and like you said didn't do their research. Then they realize they need more equipment and don't have the means or just don't want to do things right so they get rid of it.
I bought a Central American Boa recently and the seller told me he refused to sell to several people that were asking questions that clearly showed they knew nothing about the snake or snakes in general. He liked that I could easily show I knew what it needed by asking all the right questions so I was the lucky one that got her. Not all sellers would do that.