Listen, regardless of whether you choose medical school or NP school, you will be 40 one day anyway. Medical school doesn't make you age any faster or slower. When you're 40 do you want to think "Yay, I followed my dreams!" or do you want to think "I've been an NP for 10 years and I feel unfulfilled."
NP is great, and they can do a lot, but there are limitations and issues. For one, there are currently less than 20 states where you can work without entering into an agreement with a physician, which can range from paying the physician a fee (10K+ per year) to review your charts up to full supervision without any ability to practice alone. Furthermore, the NP gold rush has left the field crowded, and just as the RN field has become completely saturated with high levels of unemployment, the same is happening for NPs. As a physician, you really will never be without a job.
Other things to consider:
- You WILL have to be an RN first, even if you don't work as one, the direct entry programs require that you do the BSN-RN portion first. That's one year (perhaps longer) of working as a bedside nurse during clinicals, doing things like bed baths, etc.
- If you are really into detail, NP may not be for you. NPs are highly competent and learn a lot, but they don't often go down to the cellular level in many programs. Depending on the program, there may be many gaps in your knowledge in certain subjects.
I am going the NP route because it works for me and I think they make highly competent providers for the area I want to work in (uninsured, FQHCs). If gastroenterology is your passion, I honestly don't know if NP is the best route.