I just told 4 friends about their phones not updating to W10M (635, 1020, 1020 and 1320).
The answer from the 1320 was to go back to Android; I'm pretty sure he won't because he is happy with his phone which got after having a Nexus (I can't remember or care about what Nexus was it). He used to give pretty harsh Insider feedback because he actually thought that Microsoft could do it better after a few moments he told me that maybe to lie wasn't a good idea.
My other 2 friends (1020, 635) didn't care if they'll get the update or not. The one with the 1020 was a former Lumia 900 user; which was actually a bad story about not getting an upgrade path.
The other Lumia 1020 user just asked me to send him a link to a new cellphone with his carrier. Our carrier don't have WP/W10M anymore so, his next request was to send him a link with another carrier that has WP/W10M.
One of them (1320) felt cheated but he felt somewhat responsible for that. The 1020 owners were kind of looking for an upgrade but they were waiting something worthy of being a 1020 succesor.
My particular way to see the things is:
My old Lumia 920 didnt' got living images, didn't magically got sensor core, didn't magically got passive Cortana, didn't magically got Windows Hello, didn't magically got Continuum. So I was kind of wanting to upgrade because I was missing a lot of things by now. W10M was to me a way to access new versions of the same apps.
I still use my 920 on W10M when the 950 XL is charging and the performance is good enough for me since Oct 2015. I'm not sure what was unacceptable for those Insiders but if they were like my friend with a 1320 then I understand the rage but the rage is misdirected.