Management incompetence at several levels. Apparently the CEO and his advisors choose to execute layoffs at this speed, others below that either didn't push back (could be due to the type of CEO / associated culture) or their pushback was ignored. The end result is the organization doing things that clearly aren't in its own interest which is a management fail.

Musk brought in his own people to decide on layoffs, apparently mostly sourced among his VC friends and Tesla engineering.