FOSS GIS is incredible these days. You can do everything in open source - it just sometimes requires a bit of work. Between qGIS (+SAGA/Grass/etc.), postGIS, python tooling like GeoPandas, leaflet/cesium, etc. there's plenty of tools for different things outside the ESRI ecosystem, you just have to learn to use them. This is a long way from the dark ages 10+ years ago when much of this capability was closed source or via some ridiculously complex text interface of GRASS.
ESRI's market dominance on GIS analysis is still a big thing though but only really a hangover from the days when ArcGIS had much more capability and lock in coroporate training was a thing. Now qGIS has essentially most of the same capability, but ESRI's corporate training structures etc. are still there to some extent. It is losing its stranglehold though, especially amongst GIS 'dabblers' who don't want to sign up and lock in to a massive corporate account for whom the ESRI older-style value proposition isn't really there. qGIS is even an accepted option for local government these days in many places.
Geospatial is both complex and diverse though. There's a lot of industries there and while there's big easy simple 2d GIS markets in mining, government zoning and military, there's also a lot of other stuff going on and its all moving fast. 3d, temporal data, drone photography, lidar and satellite etc. There's lots of innovation happening there right now and new ESRI monoliths being built.