From my experience, it's useless to gauge interest at the end of the program, since everyone will still say yes to a career in research.
People don't usually move on from research purely because of money. Most people are willing to take a reasonable pay cut if the career is much more desirable. However, at the moment the research career has many undesirable components, that compare to a solid lifestyle specialty medicine career (psych or rad onc), the advantage is just not clear. Adding the $ factor then you have a high attrition.
In particular, the idea that a research career can enjoy a great degree of intellectual freedom has been oversold. Due to "malignant competition", in the last 10 years research careers are increasingly about identifying institutional priorities, protracted negotiations between you, NIH, the institution that hires you to find the right topics to project your expertise, and leverage other resources to plug holes in your research program (i.e. filling salary support when there's a funding gap, hiring part time staff when the budget is insufficient, etc et). Many grant applications will be filed because they support a team, not because they are interesting. Cooperative agreements and large multi-site grants are more common. Management is also much more corporate: typically your skill in securing funding (rainmaking) is judged more than the actual originality of your ideas. In fact, people are routinely discouraged from pitching original ideas because they won't secure enough $.
In other words, these days you should go into research because you enjoy the process of rainmaking and being a good "team player", and be fully prepared to do things you don't care about, not because you want to do some cottage industry science of some obscure topic of narcissistic interest.
