Complex sentence: Because the payload is accelerated to velocities greater than required for orbital velocity by the time the payload has left the device, the accelerations required to accomplish this a huge, making this an ineffective means of transporting humans or sensitive equipment to an earth orbit.
Split into simpler sentences: Because the payload is accelerated to velocities greater than required for orbital velocity by the time the payload has left the device. However due to the large forces required to accelerate a payload to orbital velocity, terrestrial transportation becomes impracticable when it comes to transporting humans or sensitive equipment to an earth orbit.