In popularity Unix is not the main OS for most developers. However, FreeBSD and jails, are used by the worlds largest companies. Netflix is famous for it but there are many examples. In my opinion the popularity of the OS among developers might be one of the reasons. Unix seems hardcore compared to Linux. I started to look at FreeBSD when I needed the network power, now I don't use anything else.
For starters; Try GhostBSD - FreeBSD with a MATE desktop.
Developers aren't "scared of UNIX". They are scared of things they don't know, and "don't know" in this context means Google search page doesn't explode with results when they search for the thing.
Anecdotally, people in storage business are much more familiar with FreeBSD due to FreeNAS and ZFS in general, but as some of my colleagues who previously worked for Dell EMC "storage division"^* recalled, the second most popular platform they had to adapt their storage solutions for was AIX... (and that trailed far, far behind Linux). It's also funny, in a way, since internally, they often did use FreeBSD in various departments because of FreeNAS. In a similar company, our home directory on dev. server was backed up by FreeNAS (we were also developing a storage product... for Linux).
----
* - There isn't really a "storage division" within Dell EMC afaik, just a bunch of different storage-related projects. I just had to describe those projects in some way.
> In popularity Unix is not the main OS for most developers.
Because of FreeBSD don't want to be helpful? Had idea of Jails but had no resources to make it usable for developers? What's your opinion, knowing FreeBSD backstage?
Linux, MacOs and Windows are better environments if you want drop-in solutions. FreeBSD does not have a desktop environment (Use GhostBSD for that or add something custom). FreeBSD does not support Docker because it has better solutions in place.
It can be a headache to set things up when you are new to Unix. Don't expect that the latest version of some Jetbrains IDE is 2 commands away. Compiling and other solutions might be needed.
The community of FreeBSD is very helpful. The forum and several maillists are the best way to go with questions.
For starters; Try GhostBSD - FreeBSD with a MATE desktop.