Depending on the definition of RSE, I may or may not have been one. The company I worked for was a Synchrotron Light Source; I worked on software for data collection on X-Ray beamlines. I would say that only about half of those in the same role as me had a PhD.

Moving away from data collection to analysis, the fraction of PhDs went up, but only reached 1.0 when considering the sub-group specialising in structural biology.