Q: Should you pay to publish in an open access journal? Why or why not?

There are many journals which don't require you to pay for publication (pay to publish). Please see DOAJ https://doaj.org/. And to make your journal article or any scholarly work (manuscript/data), you may share the same via Preprints or Postprints repositories. And if you decide to publish your article in a journal which is Open Access and charges you to pay to publish, you can take a call based on availability of funds. But be cautious about some journals which are not of repute which only charge you for publication and does not do any peer review either before or post publication. They are doing business for their own self profits in the name of scholarly communications. You should be aware of them. See https://thinkchecksubmit.org/