No, it is not too risky to move across the country for a job, because jobs are very hard to find. In today's world, a college student is lucky if they can find a job in their field after they graduate. Wherever they need to move, the rest - church, community, family, can fall into place. The job is the best and most important thing in a young person's life.
If the job is a good opportunity for the person's career, and they are comfortable making a change, it is not too risky. The candidate should ensure that the company is stable, and that the salary matches well to the living expenses of the area. If the candidate is focused on their career advancement, and the job is a step up, it is a great decision.
If the job is a dream job that cannot be found in your area, then go for it. You have to be happy with your job and although moving across country is a big change, it can be a change for the better. Takes adjusting, but could be worth it.
When considering taking on a new job across the country, there is a feeling of uncertainty compounded by the simple need to move. Employers are seeking out the best candidates for positions, and to be selected for a job on the other side of the country is indication of the net value of someone's skill set.