In my former office, a staff under investigation for major offences against company policy thought it best to implicate a few other people in his issue and they were all shown the exit. I wondered why he took that course of action and while I don't have the details of events that played out, it made perfect sense to me behaviourally to see someone who knows they're sinking looking to drown others alongside.
It's funny when people make plans on the actions of others. I have learned my lesson a few times that I now find it ridiculous. Human beings are both fragile and unpredictable. As much as a certain level of trust is needed to operate, it is almost naive to see a case of absolute reliance on another person.
It is especially true when we are incentivized to be selfish. Let's face it, in today's World we are certainly incentivized to act solely on our own behalf in a lot of things. It's a me-centric World and no surprises that people are a lot more selfish. Even those who seemingly take actions on behalf of others have more selfish intentions hidden in their actions.
It probably should be the norm to expect that people act in their own self interests but it sometimes isn't. We tend to be naive and get carried away by sweet words or intentions rather than actual actions on display. Then we act rather surprised when actions are taken in the opposite direction of what we imagined.
I have come to expect the bizarre when dealing with people because irrational behaviour is simply in our nature.