I’ve tried once. People h a t e you for screwing the littlest thing up. They make it no fun to play, and seriously, legendary/ascended rings and armor don’t seem worth it when you’re sacrificing your positivity for it.
At the end of the day, it really depends on what you wanna do in the game.
Personally the one time I entered a raid instance, I had a positive experience. I participated in four tries and we were able to take VG down to 56%. I had no meta set up ( I did however chose the traits that were best suitable to the encounter), no food and no utility to consume. It was a training group with a very low entry requirement.
I did not want to take part more into raiding however. Simply because I wasn't motivated to pursue that goal.
So if you are new and you want that legendary gear or any other rewards associated to raids, don't try to LFG it. Join a guild that trains people to do it or a friendly guild with people you know who has a minimal interest in doing raids.
Definitely look for a guild that is friendly enough for your tastes (which might not be as easy as people will make it out to be if you're not on EU server, but is definitely doable).
As for pugs, there's no easy way around people wanting speed clears from you even if they aren't pros themselves. I get very anxious when people start remarking about the DPS they're measuring and saying random stuff about performance when I can't answer (mute so gotta type everything). So when people start doing it I usually start messing up even more. What works for me to live with these people is to tell them I'll leave if the matchup doesn't work which actually always had people help me out in Fractals and at least never had people mad at me in Raids. Thing is though, I had fun after putting myself in this position, because people are more willing to help someone they deem as a newbie (even if a little condescending sometimes...), and there's nothing wrong if this doesn't sound like fun to you. But you'll probably have to find fun in another content.