Two things:

1) Modern 2010s era "OSI Approved open source" is a meme built by hyperscalers to get free work, poach the efforts of others (Amazon makes hundreds of millions on Redis, Elasticsearch, etc.) and eliminate the threat of smaller players.

There are great things like Linux and Blender and ffmpeg. But there is also a concerted battle waged by trillion dollar companies against us using "open" to salt the field of any kind of economic growth salient.

By being completely open and not keeping some leverage, you ensure you cannot make the same revenues the big companies can. And they will outspend and outgrow you. They will encircle and even find a way to grow off of your labor while you don't see so much as a dime.

2) You wouldn't be on the internet right now if you really refused to use closed source. The binary blobs in your hardware, your ISP, your wifi. Not even Stallman can do it.

I love open source. But I hate how difficult it is to make money. And I hate how the big players have used it to enrich and entrench themselves by making it just the crust of their closed source empires.