I think that lots of people experience these things at some point in life to some degree, and it is a temporary state for most people that does just go away on its own. It depends on their life experiences and how deeply they have been affected by them. One person may have more obstacles than another depending on their background.
For many people the difference is one of how fixated they become on the symptoms. When we become obsessive about DP we can inadvertently be reinforcing it. By worrying about it all the time we can actually be practicing it, like a bad habit, and thoughts are habitual. This is why people commonly talk about doing everything you can to focus on anything else but DP.
It can be hard not to think about something though! Fortunately, just as old habits were established through repetition, we can actively overwrite them with new ones. We can replace old destructive thinking patterns with new adaptive ones. We have more control than we realize. One way is to keep reinforcing the thought of freedom from all of these symptoms, as though you are already recovered. This acts as instructions to your mind. This is the opposite of always dwelling on and reinforcing them. Try it for a few weeks and see if it helps