Is it secure to still using an old version of VMWare ESXi for production after support ends?
Solution 1:
Short answer is no, it is not secure.
If you want to keep data private, you need to apply security updates regularly.
Otherwise you are risking that a serious vulnerability allows accessing your private data, which will have bad consequences for the business.
I suggest that you look into migrating your systems to cloud, where you don't need to worry about managing infrastructure and its security, you can only concentrate on your application's security.