It's not an all-or-nothing decision. You can think Stallman is correct, but only heed parts of his advice. I use a lot of open-source software in part thanks to the inspiration I found in the free software movement. But I haven't became a 100% purist. For example, I use some open-source things that probably aren't perfect (and hence wouldn't merit RMS's unconditional approval) such as Ubuntu, Chromium, etc. And I'm also willing to use a proprietary piece of software if is significantly better than the FOSS alternatives.