Is the condition of mechanical equilibrium sufficient for the existence of a star as a whole object?

Not. The condition of thermodynamic equilibrium must also be satisfied in the star: all the heat released in the interior of the star during the same period of time must be dissipated in space. Otherwise, the star may explode.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.