First, licensing for USMLE requires passing 3 exams, Steps 1 through 3. Step 1 and 2 happen in medical school Step 3 in your intern year. Step 1 went pass/fail a few years ago. The idea is to not give too much weight in residency applications to scoring well. But all that's happen is that program presitage is now a more important signal.

Second, most of the cost of an education comes from medical school, not undergrad. Medical school can easily run $60-70k/year. So you'd save time on a 6 year program but not necessarily much money.

Third, how prestigious is that medical school? This really matters for residency. For a medical school education to work as a doctor in the US you really have 3 options:

1. An MD program;

2. A DO program.

3. An international (typically Carribean) program.

They are ranked from most to least prestigious, so much so that even though international students who participate in the match process still have a relatively high overall match rate, they almost never match into highly-competitive specialties.

The point is you can save money but you might be limiting yourself to being an internal medicine or family doctor.

The military is another option but that's a whole other topic with various advantages and disadvantages.