The ignorance... it burns.
If you have had an engineering mindset for a long time, you will likely regret every second of not studying it during college. It's probably your one and only shot to do it. Of course you may regret the work it will take to major in it, but again, if it is what you love you will regret that less. If you take the mindset that college is just something you have to do to get into medical school and not an opportunity to explore your interests then 1) That saddens me 2) you probably will end up an engineering "horror story".
If you want something bad enough, you will do what it takes to achieve it. If you want two things bad enough, you do what it takes to achieve them both.
For those saying major doesn't matter:
EVERY SINGLE interview I had, the first thing mentioned was my major. To say that my interviewers didn't consider it when trying to grasp who I am and what I can bring to the table seems factually incorrect from my experience. Maybe the major itself didn't give me an "advantage" but the skills I gained from it, the things I learned about myself because of it, and so many things I would directly attribute to my major probably did give me a better shot at receiving an acceptance. People act like you major is a "name tag" you wear, but certain majors foster specific skills and experiences. Yes, these things can overlap, but not always and not entirely.
I do not have a "stellar" GPA, but a good GPA for my type of engineering. I do not have an amazing list of ECs, but have a couple I was really passionate about. I still got over 5 MD interview invites and acceptances to every one so far. You want to know why? Because this shallow notion of "high GPA, high MCAT, great laundry list of EC's" is exactly that, shallow. They want a diverse set of students, coming from all types of knowledge bases, ethnicities, and life experiences. Also, I think schools admired the fact that I didn't consider college just another step in becoming a doctor.
I would never trade the terrible times (all nighters) in for the world. It is a part of who I am, and I loved what I learned. Best part, I know I will continue to use it in research (I have been for a while in medical research). I learned skills I find to be very empowering, and I am glad I took the time and effort to obtain them. If you think you will share that feeling, you should do it and not look back. Of course not everyone would end up feeling that way so take my experience with a grain of salt and figure out what you project YOUR experience will be. I just thought it would be good to hear from someone outside the SDN hive mind. PM me if you have any questions or concerns.