This is misrepresenting FOSS quite a bit. A lot of open source software is indeed this permissive, but not all of it. It's important to refer to the license of each individual project because various licenses have different terms.

Some open source software may be free for personal use, but that license may not extend to other companies seeking to profit off their open source and good will. ZeroTier comes to mind as an example of this.

Further, other licenses like GPL only requires that you make your sources available upon request but you can require that your customers pay you to receive the product: i.e. RHEL. At the end of the day, FOSS means free as in speech, not free as in beer