You could package and sell a FOSS (and free/open hardware even) device tomorrow. The license doesn’t forbid it. Some have even built businesses on this!

It’s also possible to run service businesses that produce FOSS, like Bitwarden for example.

“Good” businesses get outcompeted on price by “bad” businesses, not by FOSS. Want a powerful workstation that is 100% open POWER architecture? Only $10k from Raptor Computing. Willing to go a little lower spec and use x86? Get one from Purism or System76. Reasonable, but still more expensive than mainstream alternatives, and user support on the software side is still mostly driven by the community.

Most FOSS is still finicky and geared towards either devs or “power user” amateurs who wouldn’t be paying for a license or subscription anyway. It’s getting better in some areas, but it’s generally not there yet.