I also think its noteworthy that since Sports Med is a fellowship, how you practice it will be affected by your base residency. Ortho will allow you to operate, EM will have more of an emergency management focus, FM will incorporate primary care, PM&R (an often forgotten pathway) will have a rehabilitation slant, IM will be focused more to primary care as well, but only for adults, while Peds will only allow you to work with children.
You will make the most money in ortho because surgeries just reimburse more, but the ability to do joint injections in the other specialties are also lucrative (the extent of training for injections may vary with residency training though). Depending on the market and competition, I dont think the numbers described above are at all unrealistic.
I also do not agree that ortho is the best way to sports med. If you want to do sports but hate the OR, ortho will make you miserable. If you want to do sports med, pick your favorite of the specialties that I mentioned above--its rare that a physician makes most of their check from exclusively sports medicine. Its better just to do what you love and tack on the sports fellowship later.
Sports docs often try to work for teams at all levels, but they also have patients walk into the clinics they run in their own practice. I have even shadowed docs that have worked marathons and even the olympics. Sports med is beautiful because you dont have to work with only athletes, you can deal with all kinds of musculoskeletal problems in any patient population (probably the most common complaint to the PCP, and what we are the worst trained in).