Is it possible to profit from organizing a career/job fair?
That said, you must know your numbers and develop a sound plan--the profit doesn't "magically" appear. Will you have enough job seekers? Will you have enough companies wanting to rent/purchase booths? Will you be able to justify both in seeking sponsorships?
There are a lot of variables to consider, but if you can make the numbers work, it could be a business model you could continue to take "on the road" to different locations.
All the best.