Hmm, OP from the title I was assuming the real-time brief history or kind of article-like thread but seems like here Op's asking for guidance from the seniors. In way in this way as well this thread can help a lot in learning about ETF and its History whenever a Newbie goes through it.
So here in the current Bull-Run, the most supportive narrative for Bitcoin is the ETFs, You can imagine their over_hyped performance by the recent market momentum a ticker listing completely reverses the entire market sentiments a fake ETF approval news, pulling the market from a tight range to a massive Rullish Rally.
On the Question of why they're not approved because currently, SEC doesn't want them, other countries I'm not sure how they are building their crypto policies, currently in recent times Australia has been doing some how good, for the ETF approval in the USA it's expected to be soon in near Q1 of 2024. They're currently delaying the approval request on baseless excuses, a Future ETF gets approval at the same time a spot ETF is considered suspicious due to the volatility of the market, and blah blah. Grayscale's case proved to a massive support in getting ETFs approval sooner or alter. This rally will bring a lot of wonders so expect the unexpected.