Not everyone knew about bitcoin before 2017. It was all over the internet at that time because of the peak bitcoin price reached in that particular year. Many new people invested into ICO's and business opportunities were created with bitcoin.
Most people had probably already been exposed to media coverage on Bitcoin by then. ICOs or the ICO craze as I like to refer to it as; just ballooned the popularity of cryptocurrencies, probably beyond what any of us would predict at that time. I'm still not sure if ICOs benefited Bitcoin or if it's something that tarnished Bitcoin, and therefore prevented further adoption. Bitcoin was already doing good things before 2017.
However, it's true a certain amount of adoption came after ICOs started to collapse. Then we had the NFTs, but not to the same scale, and we'll likely have something comparable in the near future.