Gravity and thermal energy are universal phenomena which compete over the stabilization of astrophysical systems.The former induces an inward pressure driving collapse and the latter a stabilizing outward pressure generated by random motion and energy dispersion.Since a contracting self-gravitating system is heated up one may wonder why is gravitational collapse not halted in all cases at a sufficient high temperature establishing either a gravo-thermal equilibrium or explosion.Here,based on the equivalence between mass and energy,we show that there always exists a temperature threshold beyond which the gravitation of thermal energy overcomes its stabilizing pressure and the system collapses under the weight of its own heat.