The way that big FOSS apps succeed is either by...
1. Catering to the needs of developers, such that the user community is also the development community.
2. Bootstrapping off of hobbyist users and crowdfunding to keep developers on board.
The second option is how Blender happened. It started out as an in-house tool at NeoGeo[0], then got sold as a proprietary shareware app by NaN Software, which went bankrupt. The fact that it was shareware meant they had a large hobbyist fanbase - it was very cheap compared to professional tools. So people were willing to crowdfund it; they were able to buy the software copyright off of NaN's creditors; and that enthusiasm continued for multiple decades until it became the massive behemoth that it is today.
For us to get a FOSS CAD app we need hobbyist buy-in. That's arguably a far smaller audience than hobbyist CG artists. And even then we have to compete with the free tiers on modern subscription apps. Blender's only competition back in the day was pirating Maya; but FreeCAD and friends have to compete with the cut-down hobbyist license on Fusion 360.
The 3D-printing crowd might be something though, it's getting very popular lately. They are often into open source and creating things so if you get them annoyed enough, there might be a competing product in the works :-)
1. Catering to the needs of developers, such that the user community is also the development community.
2. Bootstrapping off of hobbyist users and crowdfunding to keep developers on board.
The second option is how Blender happened. It started out as an in-house tool at NeoGeo[0], then got sold as a proprietary shareware app by NaN Software, which went bankrupt. The fact that it was shareware meant they had a large hobbyist fanbase - it was very cheap compared to professional tools. So people were willing to crowdfund it; they were able to buy the software copyright off of NaN's creditors; and that enthusiasm continued for multiple decades until it became the massive behemoth that it is today.
For us to get a FOSS CAD app we need hobbyist buy-in. That's arguably a far smaller audience than hobbyist CG artists. And even then we have to compete with the free tiers on modern subscription apps. Blender's only competition back in the day was pirating Maya; but FreeCAD and friends have to compete with the cut-down hobbyist license on Fusion 360.
[0] No, not that one