The first question is: What is bai‘at? To explain it, I will quote some ahadith of the Holy Prophet Muhammad(sa) and sayings of the Promised Messiah(as).
The Promised Messiah(as) says:
Bai‘at truly means to sell oneself; its blessings and impact are based on that condition. Just as a seed is sown into the ground, its original condition is that the hand of the farmer has sown it, but it is not known what will happen to it. If the seed is of a good quality and possesses the capacity to grow, then with the grace of Allah the Almighty, and as a consequence of the work done by the farmer, it grows until one grain turns into a thousand grains. Similarly, the person taking bai‘at has to first adopt lowliness and humility and has to distance himself from his ego and selfishness. Then that person becomes fit for growth. But he who continues to hold on to his ego, along with taking bai‘at, will never receive any grace. (Malfuzat, vol. 6, p. 173)