VirutalBox is a barebones type 2 hypervisor with only basic orchestration, backup, networking, management features, if any.
ESXi and the VMWare products built on top of it (vCenter/vSphere) are not even comparable to VB, other than that they both can run virtual machines. vSphere can move running VMs between storage or compute hosts without interruption, can failover between storage or compute, can failover between networking outages (thanks to virtual switches and the ecosystem of hardware support around it), and provides a platform for additional third party add ons for automated backups and recovery. Not to mention easy role based SSO access. My entire university's infrastructure was virtualized on VMWare aside from a few domain controllers and the Netapp storage clusters it all ran on, and the equally large Linux/KVM infrastructure and the HPC datacenter that ran a bunch of other stuff for...reasons (higher ed is fun). And as an added bonus, desktop type 2 hypervisors like Workstation or Fusion integrate perfectly into it. I used to manage a dozen Windows and Linux VMs straight from VMWare Fusion on my Mac and still do at home in my little VMUG cluster.
It's like comparing a Chevy Spark to an aircraft carrier, except you built an entire medium to large sized organization's infrastructure on top of it. You can't just switch overnight unless you want to stop making money for a while. For most orgs who can justify the already steep price, moving away from VMWare onto something else will mean multiple years long projects requiring thousands of person-hours to complete, redundant efforts (as the old stuff can't just go away until the new stuff is battle tested), on top of probable hardware purchases since VMWare and its demands have shaped on-site datacenter spend, layout, and networking for years.
The actual VMs are the easiest part to move since they are just some virtual disks and a config file. It's all the other supporting stuff and high availability that need to configured and battle tested that will take forever. It's not something you can plan to do ahead of needing to do it because doing so would mean doing the same job twice for years for a bet that you can't just weather some higher costs for a year or two before you can move stuff onto cheaper platforms (and train/hire for expertise).
ESXi and the VMWare products built on top of it (vCenter/vSphere) are not even comparable to VB, other than that they both can run virtual machines. vSphere can move running VMs between storage or compute hosts without interruption, can failover between storage or compute, can failover between networking outages (thanks to virtual switches and the ecosystem of hardware support around it), and provides a platform for additional third party add ons for automated backups and recovery. Not to mention easy role based SSO access. My entire university's infrastructure was virtualized on VMWare aside from a few domain controllers and the Netapp storage clusters it all ran on, and the equally large Linux/KVM infrastructure and the HPC datacenter that ran a bunch of other stuff for...reasons (higher ed is fun). And as an added bonus, desktop type 2 hypervisors like Workstation or Fusion integrate perfectly into it. I used to manage a dozen Windows and Linux VMs straight from VMWare Fusion on my Mac and still do at home in my little VMUG cluster.
It's like comparing a Chevy Spark to an aircraft carrier, except you built an entire medium to large sized organization's infrastructure on top of it. You can't just switch overnight unless you want to stop making money for a while. For most orgs who can justify the already steep price, moving away from VMWare onto something else will mean multiple years long projects requiring thousands of person-hours to complete, redundant efforts (as the old stuff can't just go away until the new stuff is battle tested), on top of probable hardware purchases since VMWare and its demands have shaped on-site datacenter spend, layout, and networking for years.
The actual VMs are the easiest part to move since they are just some virtual disks and a config file. It's all the other supporting stuff and high availability that need to configured and battle tested that will take forever. It's not something you can plan to do ahead of needing to do it because doing so would mean doing the same job twice for years for a bet that you can't just weather some higher costs for a year or two before you can move stuff onto cheaper platforms (and train/hire for expertise).