I left reddit a little over 2 years ago, I think. And have not looked back.
That being said, I'm also keenly aware how painful the out of the box experience on Lemmy/PIefed can be because of the constant drama and a seemingly joyful and endless desire to hate on whatever/whomever some groups or persons feel entitled to because they don't like them or their ideas.
Most likely, I would have left almost as soon as I joined after I started reading the default feeds and reading some threads... had I not learned to use the filtering/blocking tools... And also, learning that I could find and use different instances, some of them not filled to the brim with that sad kind of serial haters.
Imho, one of the most helpful thing to help new users realize it's a nice place that is worth investing their time and energy in, would be to reconsider how each instance is presented/summarized, and then considering how to invite potential new users to become actual users... by helping them chose a better suited instance to begin with and show them how to use the filtering and blocking tools to tailor their home feed by removing whatever they consider noise or inappropriate content. I mean, most days I'm not disappointed opening my home feed, I'm seldom confronted with low quality content... and the few really painful trolls I'm faced with from time to time I learned to only deal with them once, but that is only thx to the filtering/blocking tools I learned to use, had I not learned to use them I would have deleted my account.
Disclaimer: I'm getting old (not far from my 60s), and even though I use GNU/Linux I'm not that much of a geek. And I'm fine with both ;)
edit: (too many) typos.