It doesn't seem likely that this result is a function of either inexperience or low pay. Most of us get paid far less than the co-pilot is said to have been paid; many professionals with student loans are paying more than 40% of their present job's salary for their training; and it further appears to me a disservice to the overwhelming majority of professional pilots with integrity, to imply that being disgruntled with pay and conditions could instigate such a murderous outcome.
Quite, it seems rediculous to imagine that someone who has probably wanted to fly jets for a very very long time would go through all of the training, get the job and then a couple of moths later do this because of his contract or his pay and debts. I remember the first few months of jet flying and I am sure like most of you I was over the moon, couldn't wipe the smile off my face!