I found a very good masternode article, which explains things very well.
It’s called “ Masternodes explained in easy to understand language” and it’s written by 
https://steemit.com/kr-exchange/@shortsegments/masternodes-explained-in-easy-to-understand-language
This article explains how masternodes are really a form of passive income like a bank certificate of deposit.
Certificate of Deposit
You must have money that you can invest for at least one month. You deposit money into a storage container called an “account”.. You agree to keep your money in the “account” and not spend it. The bank uses your money to facilitate other people’s “financial transactions”. The bank agrees to pay you money called “interest” for using your money.<
Masternode
You must have money, that you can invest for at least one month. You deposit cryptocurrency into a container called a “wallet”. You agree to keep your cryptocurrency in the “wallet” and not spend it.
The coin blockchain uses your cryptocurrency to facilitate other people’s “financial transactions”.
The coin blockchain agrees to pay you money called “rewards”for using your cryptocurrency.
You get paid “rewards” based on a predetermined percentage. You get paid “rewards” based on a predetermined schedule.<
In both certificates of deposit and masternodes:
You make money every day without any work from you.
You even make money while your sleeping.
This is called a “passive” investment.
References