Here are 3 reasons why you need to register multiple domains:
1. Random people may buy your domain to trick people – Believe me, there are people out there who will buy your domain just to trick other people. This is not an accident. There are people who are looking for domain names to drive traffic to their own websites and if your domain is the best way to drive traffic to their website, they will certainly buy it. At some point, you may try and ask them to sell the name, but they may charge any price they want. This is an awful situation and there is no way around it. If something like this happens to you, find the best way possible to convince this person that this is your domain and it belongs to you and your brand.