If it's open source, people are free to redistribute it. Copies of open source software can be sold for money, but open source licenses allow redistributing the software for free. In practise, that means most people won't buy the open source software from a seller, they will choose instead to get a copy from someone who is willing to redistribute it free of charge.

Yes, it actually means that.

https://opensource.org/osd

> it just means the source is open, viewable

That's called source-available, unless "use it as per the licensing" includes further freedoms