What is the reason for jealous and envy in this world?

Answer 1

Its human nature. It is the byproduct of competition which we all need to survive in this world. It's instinct. Those who are jealous and envious should try and be a little less jealous and work harder to get what they want for themselves. But unfortunately we are not a perfect species, so the harmony will never come like we want it to. We can't even solve global warming or control our own population.