"And this is the verdict, that the light came into the world, but people preferred darkness to light, because their works were evil." Between darkness and light, it is clear that light is better. People only prefer darkness when they have a secret, when they have something to hide. We all have secrets. There are things about each one of us that the world does not know. The question is whether we would welcome the light that would reveal our works to the world. If our secrets are about things we are not proud of, we would rather have them stay in darkness. If our secrets are about things that we are proud of, we will welcome the light.
For instance, perhaps you have helped someone. Maybe even that person never realized how much work you did to help them. Certainly no one else is aware of how helpful you were. You do not walk around bragging about helping people, but if this was revealed you would not be embarrassed. If, however, you have some secret sin that no one but God knows about, you will not be glad to hear that everything you have done will be revealed to the world.
Real life is more complicated of course. We all have secret sins we are ashamed of. We all have secret ways in which we were good that we would be glad to have revealed. Beyond this, we do not really even know ourselves very well. When all is revealed, we will be just as suprised at how our sins and our good works add up. When the light comes, nothing will be hidden anymore.
St. John says that people preferred darkness. He does not say "some people". We all prefer darkness. None of us have done such good things that we would stand up to the scrutiny of the light. We would not mind if more people knew how good we have been, so long as no one also knew how bad we have been. What we need is humility. When we have real humility we will not fear the light which is truth anymore. What is the truth? We are sinners, but God loves us. Once we have real humility we will not put so much value on hiding our sins and show off our good works. When the light comes it will show how weak we are, but we will not be embarrased. We will not be thinking about ourselves at all.