Will you try and build your own forum software if there are enough resources at your disposal? How different will be your software from the existing ones?
I would love to give a try at building my own forum software if I had the tools, resources, and knowledge to do so. Sadly, my coding skills are minimal when it comes to building such a foundation. I've been using forums for about 2 decades, so I would think I could use all of the ideas I've seen on forums over the years to create something new and unique, but I would have to ponder on that one for a while.
Hiring developers is not difficult these days. Especially remote working developers who do not charge an arm and leg.
A good budget and you are good to go.
It is true that a seasoned forumer can contribute a lot. A developer thinks differently.
I've done it. Even acquired one once. I wouldn't really call it a "software" but I had a site created in python that had a custom forum on it.
Would I ever do it again? Definitely not. Why reinvent the wheel when there are options out there. I'd rather develop custom stuff for an existing software then to build one from scratch all over again.