You clearly haven't seen calculator sales this decade or last. TI and Casio have absolutely crushed HP. Both are infix. Coincidence? (maybe, who knows...?)
Don't get me wrong, my HP 48 and RPN rocketed me through 4 years of EE. But most of the other pre-Es in my classes used TI-8x and Casio FX-xxx, I assume partly because they didn't require a tutorial to do the simplest things.
So, be careful rolling out the "most popular among X" argument. Not surprisingly, that almost always supports the infix crowd.