A few thoughts come to mind.
Fred is right. Struggling companies need more help.
And VCs I have worked closely with tend to dig in more when things are hard. Inside rounds, recruiting, hard conversations with the founder, layoffs. All painful, all require time and much harder than it looks.
I have also seen VCs “cut and run” so to speak. It’s more of a drift away than a run. Yes, sometimes this happens because the VC is lazy, unable or unwilling to help. Other times VCs drifts because they are fatigued of a founder controlled company where the board is unable to impact change. So they drift.