Well, for starters you might be more attractive to Pharma. So then after all your years toiling for the MD-PhD, you have the potential to get big monetary reward 😀
Also, you never know whether you might become interested in a competitive residency... ON the Plastic ROAD (oto, neurosurg/possibly neuro in the future 😎, rad/rad-onc, opthal, anes, derm, and plastic is plastic)
Having a MD-PhD just makes you more attractive to everyone -- no matter what job you're trying to apply for -- residency or Pharma or whatever.
Besides, MD-PhD would have time to start a family in med school. Give you some time to chill out and relax a little. Live your social life while cranking out some quality publications in time for your residency/other-work apps sounds like a good deal.
Also, not to mention -- as MSTP, your schooling is wholly paid for by the US government, so you don't have to take loans... and you get a stipend. And during your PhD years, you could work as a TA and start making some money. If you invest wisely, you're actually a step ahead for building your portfolio than most of your MD classmates.
All around. It's a good deal.👍👍