The sad part is that most companies using VMWare could have been using Proxmox all along without any of the licensing and fee nightmares.
As a user of Proxmox, and observer of VMware infrastructure in other silos in some IT orgs I've been in, there is no way that Proxmox was a viable solution 3-5 (or more) years ago.
Hyper-V could have been used in many instances. I know a few places that chose to start moving to Nutanix even before the Broadcam fiasco. OpenStack is useful for many large scale environments (especially with tenant isolation and usage tracking/billing/chargebacks).
Proxmox is good a good solution for SMBs, but (especially pre-9.x) there were a bunch of things that made it much less usable for large(r) scale deployments IMHO.
Define "pretty big". Proxmox officially supports up to 32 nodes in a cluster and the Proxmox folks themselves have "seen clusters of around ~24 nodes in production" (as of 2025) and for "bigger clusters than that, fine-tuning might be necessary":
* https://forum.proxmox.com/threads/proxmox-with-48-nodes.1746...
There are folks talking about running things in the high-40s and low-50s, but that's not officially support. If you have beefy hardware you can fit a lot of VMs on a single hypervisor (I've always found running out of RAM is often the limit).
A single vSphere cluster can have up to 96 nodes (without vSAN), and vCentre can handle multiple clusters (2500 total hosts; 40k VMs). Proxmox recently released Cluster Manager, which helps with feature parity.
I'm a happy user of Proxmox for a number of years (and helped ran OpenStack before that), but I think for large(r) scale deployments (and even smaller ones) there's a good reason which VMware was so popular. (How many folks are actually at that (large(r)) scale is a different question.)
(Also: XCP-ng doesn't seem to get much press. Haven't used it myself though.)
It does help that I have thirty years Linux experience compared to the paltry twenty five or so of VMware (which was RedHat plus stuff back in day)
I also have rather a lot of Hyper V exposure too and I defy you to love its iSCSI and networking, let alone that awful vTPM thingie.
It's Proxmox for me, any day. Even when I've completely knackered it I can always boot a systemrescuecd and mount and chroot the thing back to life.
I had asked for vSphere to avoid this problem, and they balked at the licensing costs even in the good ol' days.
Oh it's crude on day one? So what? You're still operating and on your own terms, and every week a few more minutes of work gets added as little pain points get addressed by whoever cares, and before you know it it's better than anything you can buy, and the total cost was less than your previous licensing, and you never had to deal with a serial number or license manager or account rep, never had to care one bit about counting cpu cores or client seats or vms or physical hosts or ips or backup copies or spinning up new dev boxes or more production without warning or any of that bs.
The bigger you are, the less you need the convenience of outsourcing, not more.
Quite often the bigger you are the more the higher ups want risk to be mitigated, and so are often glad to cut a cheque to be able to yell at someone over the phone.
Waste of money
I like Proxmox a lot, but it is technically and commercially several years behind. There is no moat, and when stuff slides sideways, you need to understand what's going on (e.g a competent sysadmin). That is changing with the recent Proxmox NA announcement, but still not there.
OpenStack is not the same product at all, and is about an order of magnitude more complicated. Much more powerful, but instead of a good sysadmin, you probably want a team (and maybe some core devs).