Career Change When You're Over 40

Oh, gosh. I hope I'm not offending anyone about this post title.

Anyway, I was talking to my very good friend Maria in Houston, Texas yesterday and was very surprised when she told me that she recently started taking classes to pursue a Nursing career. I mean, with the unstable economy and all, I guess it's no surprise why people are switching to more promising careers- the ones that are more stable and always in-demand, so to speak. My friend Maria is a smart woman with an Engineering degree and has been working as an accounts payable clerk for a long time. But since the recession and her company constantly downsizing, she developed a fear that she might get laid off from her job too. But I guess, I'm just wondering: Maria is in her mid-40's, going to Nursing school for two years, then she will be practicing as a nurse for ten years after that. Is it worth it? What do you all think?