Okay, use the Internet and computer networks in general. Network connectivity was expensive and slow until the late 90s. Computers were very expensive, further limiting reach, until the personal computer revolution opened it up and prices came down in the 1990s. Software was primitive, too, limiting reach and capabilities - people who could afford Macs or Amigas had GUIs but that wasn’t mainstream until the Windows 3.1 era, arguably Windows 95.
The pricing for hardware, software, and especially connectivity meant that this was an upper-middle-class or richer phenomenon at first and it wasn’t until the mid-to-late 90s that it had become common for lower-middle class families to have a networked computer.
All of that is completely unlike Bitcoin’s day one availability to a billion people.
Despite those barriers, because network connectivity had actual value to people who weren’t selling it, unlike Bitcoin, many normal people paid money to get access to services like Compuserv or GEnie, the earliest ISPs started connecting businesses and schools, you’d hear about people taking an elective at the local college to get a student account, etc. Technical work adopted as allowed - email/Usenet support, FTP sites, Telnet access to applications and forums, etc. were all common before the web – but so were people reading the news, getting stick quotes or researching, playing games, or socializing - the first met-online marriage happened in the late 1970s if memory serves. Real people found it useful enough to pay extortionate telco rates, deal with modems, even getting second phone lines to avoid disruption.
That all contrasts sharply with Bitcoin which arrived in a world where a billion people had the ability to use it. The lack of adoption has been due to the lack of a need – and especially the community’s tendency to say “you don’t get it!” and rant when people explain real concerns such as cost, fraud, or lack of benefit over the other options. This is a dead tell for when people have major conceptual problems: if you can’t explain a system to a non-specialist at a high level, something is wrong. The fact that 13 years in people are still unable to come up with a compelling pitch for why someone would want to use Bitcoin beyond speculation tells us that long-term success won’t happen without major changes.
The central bank analogy doesn’t work, either, because that didn’t arise out of nothing but was rather formalizing existing banking relationships with goals like stability. That evolved over centuries and, most importantly, constant daily use — nobody went from storing money in the couch cushions to a central bank without an intermediate state. Similarly, central banks are backed by some form of real value. A pure fiat currency like Bitcoin with weak backing, plenty of competition, and no innate demand is not what you’d use for such a system — and, indeed, anyone who is familiar with the history can see that’s the concept people who’d bought into Bitcoin pivoted to after failing at the original goal of being a currency.