We could have chosen Firefox (most devs seemed to prefer it), but as the market share numbers bear out, most people are familiar with Chrome; most are not with Firefox.
If Firefox had specific features that made it easier for enterprises, or even internal teams at startups, then companies would happily pay $10/user/mo for something as critical as a browser.
There isn’t any such reason afaik.
Edit:
Some examples off the top of my head include
- VPNs
- user and permission management (identity)
- ad- and tracker-blocking
- internal auto-updating and easily managed/deployed extensions