Why are organic compounds volatile in nature?

It depends on which definition of volatile you mean. In common speech, volatile is used to mean explosive or highly flammable. In science, volatile refers to a substance that readily becomes vapor.

In terms of the latter meaning, many organic compounds are composed largely of carbon and hydrogen. leaving largely nonpolar or weakly polar molecules with low intermolecular attraction and thus low vaporization energies.

In terms of the former definition, both carbon will readily combine with oxygen and release quite a bit of energy in the process. Therefore, most organic compounds are flammable. Additional, if the substance is easily vaporized then the vapor will easily mix with air. A mixture of flammable fuel and oxygen will burn rapidly, resulting in an explosion.