They may be aware that if their colleagues get fired, then they probably will too. They may be thinking that they'll be competing for jobs with people in lower

They may be aware that if their colleagues get fired, then they probably will too. They may be thinking that they'll be competing for jobs with people in lower cost of living locations and that this is likely to affect their career earnings and/or ability to stay in their current high cost location. They may just be lazy and find their job easier in the office. Note these are all entirely selfish and nothing to do with whether the employees are more productive - I think this kind of explanation is more likely to be true!