Pinboard is my secret weapon for those obnoxious lists of citations I sometimes get to spackle onto the end of comments on the internet. I've been on there since December 27, 2010 (Merry Christmas to me), and currently have 8,698 bookmarks across 1,544 different tags. I'd have a few hundred more if I could hurry up and transfer all the open tabs from ios safari. ...so I'm genuinely worried about those declining user…
My story might be relevant. I only recently learned about Pinboard. $22/year isn't terrible, but it's just a bookmarking service. Free trial? Nope - you need to pull out your credit card and fork over $22. You get seven days to request a refund. (Will I actually get it? No idea who's holding my money.) He's happy to boast about competitors disappearing, but I use OneNote, and Microsoft isn't going anywhere. Yes, Microsoft is horrible, but they're also spectacularly wealthy. Ultimately I didn't subscribe.
Businesses need to ask from time to time if their business model is the right one for the current year. Expecting people that don't know you to give you $22 for a bookmarking service, without a trial period, might be wishful thinking in 2020.