I really don’t think that you can become a fully developed human being unless you have some series of events in your life - more than one - that break down your vision of the world and provide you with deeper insight.
It doesn’t have to be psychedelics - it can be all sorts of different life experiences. It could be traveling, it could be meditation, it could be deep consideration for the world. A constant overview and a constant audit of your thoughts and the way you interact with people and your happiness and where it comes from. I think all of those are possibilities.
There are different ways to achieve the same effect. But unless you do have those things, you’re going to be a child.