Like various idea within the world, beauty is also one in them. It is the believing, or we are telling our brain what look alluring or appealing to us.
Concept itself is created primarily based on views or perspective, so if I think something is lovely then it is, since it is what I informed my brain or what my brain inform me it is, due to the impact of the society or my own ideology.
Concept is created to make life meaningful and interesting.
Beauty is primarily based on special perspectives, like everyone in the world have their views of what is beautiful, and what is not. Like if I assume what other people discover ugly is beautiful, it does not imply am wrong, but it means we have different view of what beauty means. If beauty is a concept created with the aid of our thoughts then beauty is not natural likewise it has not anything to do with nature.
Even though beauty is a concept we made up it does not imply it is not real because this idea makes an impact in our view of the world.
So, it does not matter what people assume or say, just try to find beauty in things which you do and love after all it's a concept we created, so hold on creating and making beauty in all things.