I am running a forum (about web technologies), and have been doing so for about 24 years (damn. I'm old). I had some spam problems, but was able to get rid of it.
It probably helps that I wrote the software myself (24 years ago there weren't many forum software projects).
But the traffic is declining. The peak was around 2003-2005, with >500 posts per day, and is slowly declining since then with a massive drop last year (about 19 posts per day). Young people only rarely use the forum anymore, despite massive modernization efforts, and the older people slowly disappear.
1998 | 6686
1999 | 40528
2000 | 70379
2001 | 41129
2002 | 171294
2003 | 203642
2004 | 204685
2005 | 173659
2006 | 150000
2007 | 135936
2008 | 126283
2009 | 94894
2010 | 70333
2011 | 48691
2012 | 31197
2013 | 30606
2014 | 30227
2015 | 29334
2016 | 25472
2017 | 27505
2018 | 28551
2019 | 22366
2020 | 17250
2021 | 12794
2022 | 10135
2023 | 7151
If the trend continues we will shut it down in a year or two.