The problem is that health issues and being old are linked, aren't they? I know a transgendered woman well up in her seventies, who, after having heart surgery recently, had to have her hormone therapy stopped. But, after the Standards of Care were revised last year, hormone therapy is no longer required as a prerequisite to Gender Correction Surgery, that is not such a crucial issue any more. However, just with a dicky heart, Gender Correction Surgery becomes a much bigger risk.
Another factor is that a full transition can take a long time, for not everyone can breeze through it in a couple of years, for a variety of reasons. With me, age has been an issue. I have undergone counselling from the time when I started actively seeking transition, eight years ago! I still haven't had Gender Correction Surgery. Neither have I been approved for hormone therapy yet. (And the local endocrinology clinic has lost my file yet again.)
When you get older, you do start to count the years you have to your death rather than the years from your birth, as someone observed, and you can see the road ahead ending at some point. The worry is that you will run out of road, just as you are settling in comfortably for a nice, long cruise along the highway of life.