If you're having trouble fully understanding Bitcoin, then don't worry: 𝘮𝘰𝘴𝘵 bitcoiners don't understand it! In fact, it could be argued that no one 𝘧𝘶𝘭𝘭𝘺 understands it. There is no end to the Bitcoin rabbit hole, as there is always more to learn.
The reason why it's not yet used by the majority is two-fold: First, many people simply haven't heard about it yet, or if they have, they feel intimidated by something they don't understand. And second, they don't yet see the need for it.
This second reason is mostly the case in prosperous countries, where inflation and financial censorship are still fairly minor problems. In emerging markets, however, the need for Bitcoin is keenly felt, so once people in those regions hear about it, they need little-to-no convincing to begin using it!
It's also important to remember that even though Bitcoin has been around for almost 15 years, it's still quite young. These are the early days, similar to where the internet's adoption was in the mid-1990s. Bitcoin 𝘪𝘴 being used in some places, and more businesses are accepting it every day. This growth is expected to continue, first gradually, and then suddenly.