Sounds a bit like she is "addicted" to achieving and short term successes. It's great to face a challenge, do what is needed to overcome it, and receive praise for it. But, doing a job/career that requires long term commitment, day in , day out, may not be rewarding for her. I obviously couldn't say if that's because she has a short attention span, is immature at some level, has a narcissistic characteristic, is just misaligning her interests and talents with the wrong vocation, or a some combination of the above. You can be supportive but she needs to self reflect. A neutral 3rd party she can talk to may really be helpful for her.