Son blowing all his money & I'm scared he picked the wrong college major

My son is going into his junior year of college. He's a really smart kid taking a very difficult major and on a full scholarship. My concern is that there aren't a lot of jobs in that field especially in the area where we live now, and it's extremely competitive to get the few jobs that are available. I follow a sub for his major/field and all the posts there are very depressing from people who graduated with excellent credentials but can't find jobs anywhere in the US. I think my son should change his major now while he still can to something more in demand with better job prospects, but he doesn't want to hear it. My husband doesn't want to hear it either. We are poor and can't afford to support our son forever and we also don't have the money to pay for another degree after the scholarship money runs out. I send them both articles about the job market in that field but I don't think they even look at them. How can I convince him to change his major now, before it's too late?

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Also, on a somewhat related note, in addition to going to college full-time, my son also works 2 part-time jobs (a total of 30-40 hrs/wk). He makes quite a bit of money (for his age) but he spends all of it on mostly stupid shit he doesn't need. He's not saving anything. How do I convince him that it's important to save at least a little something for the inevitable rainy days that appear to be imminent in our future?