50% of all physicians in geriatric medicine are IMG not 50% of all IMG are in geriatric medicine. The pool of physicians in geriatric medicine is small (pediatrians outnumber them 11 to 1), majority female and on average, very young (vast majority are under age 55). i suspect IMG go for it because US docs aren't interested and because many jobs in outlying areas, where US grads don't want to go, have large populations of elderly and a demand for physicians who specialize in care of nursing home patients.
I've worked with many geriatricians over the years. They tend to enjoy medical complexity and the challenge of dealing with families and the legal and social issues that arise in this age group and working in a team to solve problems. Some choose to focus on the care of nursing home patients and to help them maintain their dignity and quality of life at the end of life. On a personal level, they are a varied lot: some love old folks and had happy memories of their own grandparents or other elders, others go into geriatrics because they fear aging and want to work to avoid the perils of old age. Some practice in in a clinical model that provides consultation to primary care providers while others are primary care providers for complex patients (particularly those with impairments in memory and executive function) and do the care coordination among specialists (eg. neurology, cardiology, orthopaedic surgery, ENT, etc.)
