Edit: the following statement is incorrect and retracted: ‘Virtualbox is not free for commercial use iirc’

Esxi is an enterprise product which engineers are familiar with, the cost of the product vs the cost of migration and upskilling in alternative tech should not be underestimated, particularly when it’s the thing that runs all your other things.

Edit: in case you’re not aware, many organisations still leverage on-prem virtualisation technologies - that might not be obvious to people that haven’t seen it.