My dad got a 300 baud modem in '84. I believe that was hand-me down for me by '86 when he got a 1200 autodialing modem? I wasted a lot of time on Compuserv on his computer. Either way I started mid 80s. I got serious and invested my own money around 1990 I think I paid full list price for a V.32 standard 9600 baud modem around 1990. Modem protocol wars were expensive and I don't miss them, as I recall v.32 lost a battle and I essentially had a very expensive 2400 baud modem by the time of the V.32bis 14.4K around 1992 or so.

Cost: This was an era of fast hardware obsolescence. So for two (maybe three?) decades the top of the line fastest thing you can buy was around $600 today and "it got the job done two years ago at a quarter the speed" is literally free at a ham radio swapmeet or hand me down from relative, etc. You did become an absolute expert on long distance billing, and the difference between unmetered LATA calls and metered out of LATA calls, and billing rates vary by time, and strange deregulated long distance cards, etc. Obviously if you lived at the level of "hand me down modem" it was important to call the unmetered free locals and if you dropped $600 on a newer modem every year you probably didn't care about LD charges, heck those rich guys probably called international bbses sometimes...

Joe6Pack: Average people did not participate. So limited politics, no propaganda, no censoring, etc. Even Compuserv or AOL users were pretty high tech compared to average TV couch potato. There was a problem finding your FIRST BBS in a magazine or a sign at a Radio Shack store or a friend at school or something. Then every BBS you logged into and every file you downloaded usually had some tag lines for "BBSes we're friends with" and you could branch out. And much like ham radio lists of VHF radio repeaters, there were vast lists of BBSes, some of the listings were even current and valid. BBSes came and went. You leave for Basic Training in the military for a summer, come back, and a third the local BBSes are gone LOL, but in the good old days it seemed two sprung up for every one that closed. I'd say at peak there were like 10 BBSes per million population, so about 50 where I lived were toll free calling, and maybe 5% of people were also sysops of their own board, so like a thousand BBS users per million people? Makes hobbies like Ham Radio look practically universal in comparison, maybe 25 to 100 hams for every BBS user in the late 80s? I mean a popular BBS might have an active users list of 30 people and an active two meter "fun net" on ham radio might have 80-100 check-ins nightly, so when ham radio is a multiple of popularity you know there's not many BBS folks in the area.

Similar to social media: Well it was interesting at the BBS level that everyone knew who was online by being friend of friend and advertise on each other's boards and download the latest local BBS list and all that. So you tended to use the BBS where your friends were, or your friends became your fellow BBS users. So now there's Farmville, then there was TW2002. I will say the people who pushed the CGI interface for web servers seem heavily influenced by the people who wrote door games back in the 80s, some conceptual continuity if not literally the same human programmers LOL.

Industry size: Well, its like asking how big the knitting industry is. There's a boat load of people doing it but not monetizing every knot and stitch. Someone was paying a lot of money for those new $600 modems that were technologically obsolete every two years. Someone was paying a lot of money for magazine ads to sell those $600 modems. Someone was paying $30/month to the local bell operating company to get a second line to their house to host all those BBSes. Someone was paying a lot of money for large hard drives to hold warez and even legit files on their BBS. On the other hand not much money changed hands for direct use outside big nationwide services like prodigy/compuserv/aol, almost all boards were free and labor of love/hobby for the sysop.

Tech breakthrus: Someone had to pay for the development of fast modems and big hard drives, and I'd say that's the BBS folks.

BBS documentary: Pretty accurate, having been there for most of it. Note he had to edit down to fit a video time span.