Hi I have a question regarding this statement:
It is essential to understand that the private key is the most important and sensitive part. Whoever has knowledge of a private key has full control over the associated funds.
How come when you now a private key you have full access? What about brute forcing all private keys and check if one exists and has some XEM on it? Sorry if this is probably a stupid question 
Thanks!
In my opinion, XEM and other crypto coins are based on RSA(maybe) key exchange, and that’s why they are called crypto coins. Every account have a public key and a private key and brute forcing is mathematically impossible. For example if you know someones public key, it is impossible for you to get his private key using calculate or brute force or whatever. Even use up all NSA compute power, it can not crack a RSA 2048 right now.
You are spending in energy way more than current nem marketcap.
The Sun will stop burning before you have finished
The short answer is that the chances of creating the same key-pair as someone else are astronomically small. You probably have a better chance of winning the lottery twice, in a row. So go try that instead 
Thanks for the answers!
Since NEM uses elliptic curve which is not post-quantum cryptography and current quantum computing advances, are you sure this will be true also in 5 years?
NSA is already moving away from elliptic curve cryptography.