Try not to think of it as being ripped to shreds. Try to just think of it as a shotgun blast of constructive criticism. 😉
In all honesty, what I’ve learned about demos I’ve learned by making all of the mistakes myself. The first demo I put together (back in … the 90s!), contained a 15 minute long song that I had the conceit to believe people would all listen to and enjoy. The second demo I put together started with a song that built in volume slowly, which meant that people would turn up their volume thinking it was too quiet only to get blasted by their speakers 30 seconds later. Etc. Etc. Etc. I’ve made a million missteps and I’ve seen composers make a million more. The good news is that people only remember the good demos. So, if you’ve given someone a lousy demo, there’s usually a chance than handing them a new good demo won’t result in them thinking “Oh wait, I remember this guy’s first demo.”
In that way, you actually do have a second chance to make a first impression and the demo process can be pretty forgiving.