You can find this mentality in companies of any size, even if it's probably more common in medium to big sized companies. Point is that in general people that

You can find this mentality in companies of any size, even if it's probably more common in medium to big sized companies. Point is that in general people that are upper in the chain are usually pretty self-important and see themselves as indispensable, while everyone below is seen as disposable, so as soon as you drift out of their simpaties and their plans they don't care about you anymore. Obviously there are senior managers/bosses smart enough to know about those 2 or 3 people that they absolutely need to keep for reasons(they know secrets, they have some super rare skills, ...) otherwise the company will just disintegrate. Humans are selfish, as simple as that, almost nobody goes up in the company ladder for virtue, more for greed and convenience usually, so it's not so strange that things are like this.