By world, do you mean earth, or our society as a whole? I'm not sure about what's the biggest problem in our society, but I'm pretty sure our society is earth's biggest problem
Though, if I had to say something, I'd say ignorance and fear of the unknown.
People being treated depending on who they are is the biggest problem.
I really hope you mean being treated depending upon race/ethnicity is the biggest problem, and not treating someone differently based on whether or not they are an ******* or a good person would be the worst thing...
As for what I think the worst thing is...the world's biggest problem is that we are selfish. We are not willing to solve all the problems of the world, because it would harm or destabalize a few in the interim. We are not willing to help everyone else at cost to ourselves, we are not willing to work towards a common goal unless under extreme peril. All of the worlds problems stem from this. Selfish people who want wealth, selfish people who will abuse others for their own well being, selfish people who ignore others pain for their own gain, people who help themselves but frown on those but will fail to help another of the same problem. Wars caused by selfish desires for power, the selfish desire to be right. This is the world's biggest problem.
Malnutrition (i.e. both hunger and obesity) is a huge problem. The hungry and the overweight share high levels of sickness and disability, shortened life expectancies, and lower levels of productivity.
we have a meme over here that states "The world's biggest problem is YOU!". No offence
If ignoring this, I think it's general malevolence. When a person learns that the easier way to raise oneself over another is by lowering that another, he starts being malevolent, this escalates.
