They can, but the majority don’t as they just come once a month or less, and if they leave they have to go through the entire intake process again, which can cost a lot. Furthermore, if they leave they may not find the same service for the same price. It’s all supply and demand. I’m doing a very very rough comparables analysis bud. When you do actual financial due diligence for a leveraged buy out like this, you'd survey the attrition rate and factor that in. P/E is 3x which seems reasonable to me for a low small town grocer growth industry like this. A back of the envelop DCF actually would put this practice at somewhat higher value than 1M. All this is standard stuff and plenty of consultants can do business appraisal for you--the only difference here is this doctor most of the sourcing and analysis himself, with some help, presumably, of a lawyer.
It's JUST like buying a rental building. Every year some people would leave, but then you just find replacements.
Furthermore, these contracts are often structured that if you lose a lot patients in the process your valuation changes in the pay period, vaguely resembling a convertible note. OTOH, owners mortgages are backed by income streams of the practice, so the current owners often are willing to give a low interest rate.
Of course, someone not as savvy, such as you, would be all like holyshizzzballz 1M for charts never ever ever when I already have 500g of student loans. And thusly you'll be twiddling your thumb waiting in your office for 5 years. When people think about risk adjust return, they often don't factor in opportunity cost.