This is a repost of mine from a previous conversation on this subject:
My wife got a Ph.D. in molecular biology. She did a postdoc and NIH and then started to look for job. She wanted to be a professor at a University. After talking to some of the recruiters at Universities we found out they were getting hundreds of resumes for each position. In addition, the research field is brutal. You constantly struggle for grant money and tenure is pretty much a thing of the past. Universities want you to come in with grants, they take half the money, then they boot you out if you lose your grants. It's a very stressful environment to be in. Another thing I ran into while doing research was that the number of teaching positions at Universities has gone up about 50% since 1960, however the number of Ph.D.s has gone up 500%. Of course there are commercial research positions as well, but at least in biotech there is a lot of turn over as companies come and go. She has friends that get laid off every couple years and spend six months to a year looking for a new job. There were also a lot of sales jobs where you go around and sell equipment to companies, which she didn't want to do. Do you really want to spend all that time in school to be a sales person? My wife eventually ended up with desk job with Genebank at NIH and no longer does research. Note that she was 31 by the time she got her first real job. That's a lot of time to put into education for not much reward. She is especially annoyed that she will never make as much money as I do in IT even though she has a doctorate degree and I have a master's in CS. We have encouraged our son not to go into science.