I guess what comes to mind for me is that the Peterson's are not a young couple. I think they may be financially secure, but I don't think that they are by any means wealthy.They are business people, business people usually secure things like loans, even if it is their own son.
Also, they probably need to secure the loan to ensure proper medical care for Scott's mother, and retirement. To be real honest, things don't look too good for Scott, but maybe they can sleep better at night knowing that they helped him get the best defense possible regardless of the ultimate outcome. Regardless of what people think of Scott, it's their son, and they love him.
That's just a few thoughts from the peanut gallery..
Everyone have a very happy and safe Thanksgiving.