If you do not register your trademark, then somebody else could do so. This immediately puts your business at risk and any products or services you are selling or promoting.
By registering a trademark you protect your brand and therefore your business.
Once your trademark has been registered you can prevent others from using it. If they do, you can stop them from gaining momentum off the current and future success of your business.
Once you have created a trademark for your business, but do not register it, you may find that you have to cease providing the goods or services you have spent time and money building up.
Your efforts that you have put in and the reputation you have gained along the journey will all be in vain.
Changing the name of your company can be a difficult and costly undertaking.
By protecting your trademark and therefore protecting your investment, you've laid a sound basis for the progress of your business.
Protecting your Brand
Although trademark registration is not an absolutely necessity in order to protect your brand, it can be very costly if you build up your business without it.
Unregistered trademark rights are very difficult to enforce as you need to have enough evidence to prove that you have built up a reputation under that mark.
It will also be difficult to prove that the other party's use of an identical or similar name is a deceptive misrepresentation and that there is a serious likelihood of damage or that damage has already been suffered.
Enforcing unregistered rights is a very expensive and long lasting procedure compared to enforcing a trademark registration.
This is a factor if the other party believes that the owner of the goodwill cannot afford the resources needed to enforce an unregistered trademark and could be taken very lightly.
Whereas with a registered trademark, threats of infringement or damage are taken much more seriously as the legal rights obtained by registration are much stronger and easier to enforce.