I don't agree. Open Source has always been about making money. What you might mean is Free Software, which is quite different from a philosophical point of view.
Open source isn’t particularly about making money. The making money is orthogonal and potentially harder if the source is available with a permissive license. Free software is about freedom of the user to make copies and distribute the source code and again money is orthogonal.
But I think in practice both open source and free software are hard to monitise. Often the open source software is a marketing platform for a managed service ala “we made it were the experts let us host it for you”
I still disagree, open source from the start was designed with companies (and it's developers) in mind and companies are particularly about making money. It's about the underlying values, open source is about making development easier, cheaper, etc.
Btw. I'm not comparing open- vs. closed-source but open-source-software vs. free-software.
I haven't read up on the origins of OSS, so I can't really comment on why it was designed. I will at some point read up on it more.
I agree Open Source & Non-Free (as per R.M.S.) would be much more commercially useful than Free in a lot of circumstances, because if I pay $1000 for some Free as in Speech software I can then go and sell it to your competitors for $10.
The only way I can think that this is not business-destroying if said software is so tricky to set up that it only makes sense to buy it from the original vendor who will set it up for you in the price - in which case that probably breaks the spirit of free software.
That is simply not true with permissive licenses like MIT, BSD, Apache, etc. which emerged out or got embraced of the Open Source movement.
The Free Software movement on the other hand created licenses which try to prevent the kind of behavior and thus are protecting the open software going forward.