Had to think about that for a bit - it's been a while. Don't recall there being any one singular cause, but a number of factors. It was originally a site for musicians and music oriented people to gather and strut their multimedia stuff, and it accelerated into a full-blown social gathering place from there. Constraining cashflow & bandwidth - which are interconnected of course - with the expanded popularity and flexibility of the platform made it a victim of its own success. It wasn't cross-connected to pull in revenue from all over (like Facebook does), there weren't ads plastered all around the corners - just your stuff on the pages, and that was it. I recall during the decline there were some things that were getting more restricted & cut back, but can't remember exactly what all it was. Meanwhile Facebook was getting touted as the new "thing" to be a part of - I remember taking a look around that and going "bleah" - had as much character and excitement as a blank sheet of paper. And yet people jumped right into it, probably because there was no other widely known comparable alternative to migrate over to at the time. That's all I can come up with off the top of my head though there might be some FReepers around here who would have better detail and recollection than I do.