Understand Bitcoin in 2025? Do you mean on the protocol level and the technical aspect or the consumer level? Bitcoin can be tough if you eat to know about the techniques, the underlying technologies behind it but it's more understandable when you read them thoroughly and practically, where everything you do is in your front. Imagine that you are running Bitcoin node with your device, if you master everything there is nothing else will be discuss about Bitcoin node that you wouldn't have an idea about.

Don't try to know everything about Bitcoin unless you want to be a professional just like the way you say, read mastering Bitcoin, check learnmeabitcoin and some other simple books and platforms about Bitcoin, do well to also check this forum because you don't just read anything here to understand, you can also read and ask questions about anything and people that has the knowledge will contribute to your thread in details.