It's both really. Too many people rock a cracked screen, then upgrade it as soon as they can. Rather than looking after their device or getting it repaired.
But at the same time, corporations limit device longevity due to bad practices. Like limited security updates, planned obsolescence and anti-repair policies.
In short, not enough people care enough, and the companies prey on this. Attacking the "upgrade culture" is valuable, as legislating against these bad practices can only happen if the people exert enough political pressure
Same situation as plastic straws. Let's blame the public for using straws, when actually it's industries and corporate policies that refuse to adopt better practices.