Following path of karma yoga alone as expounded in Bhagavad Gita can lead to becoming a JRD Tata, not more. On the material scale, one can reach highest level of evolution but nothing compared to spiritual life, state of self realization.
King Janaka (father of Sita in Ramayana) indulged in karma yoga and also jnana yoga (path of absolute wisdom) to reach state of self relaxation in his lifetime. His mentor was Sage Jnanavalakya (composer and compiler of most voluminous Brihadaranyaka Upanishad).
Karma yoga truly means indulging in nishkama karma yoga, never worrying about fruits of karma performed. A true seeker is never dependent on fruits of karma performed. The reason for this is fruits of karma indulged by human beings always belonged to the spirit, soul atman existing in heart, the ultimate master and controller of human body.
It is our soul atman, the spirit that manifested human form to work out its karma.
Path of spirituality demands our indulgence in nishkama karma yoga, working like a trustee, a caretaker for whom everything all the time belonged to God Almighty. A seeker always is and was an instrument in hands of God Almighty doing his bidding all the time.
Spiritually all are sons and daughters of God, even lower forms of life.
Path of spirituality demands that we worked for welfare of mankind all the time. Self realization is never intended for individual self. A seeker who made efforts for individual self realization never reaches it. Seekers who worked for welfare of mankind all the time were endowed by God Almighty by state of self realization as a gift of their service to mankind.
State of self realization always followed as a byproduct of our indulgence in spirituality. And indulgence in spirituality must always be via path of nishkama karma yoga, a karma that never produces any bondage, attachment.
In simple words nishkama karma yoga means a karma that was free of all attachments forever.