Does the CGM just not work for me?

I tried the Enlite ~6 years ago, with predictably disastrous results. Since then, though, I have tried getting on the Dexcom four different times, and each time I stop using it after 6-12 months because it consistently has results that are comically off- like saying I'm 400 and rising rapidly, when I'm really 160. I've tried bringing this up to my endo and to my Diabetes Educator, but they're so into Dexcom and want me to try it again. I just haven't had good results, even with the G6. Is it just me, or is it possible that, for whatever reason, a CGM just doesn't work with me?