Your risk assessment acts as a useful checklist of what could go wrong and how you can take appropriate measures to reduce those risks.
It also allows you to indicate the ways you will mitigate against any risks you identify. The intention isn't necessarily to remove the risks, just to show that you have reduced them as much as possible.
If there is an incident as part of your event, you may be required to show your risk assessment to prove you have been diligant in your duty of care.