Reeldoop, Bool'...
The risks of using cross sex HRT are not zero, but not amazingly high. There is a gross exaggeration on the risks that occurs on the web, both by nervous transfolk and by those who would see transfolk denied medical interventions. The greatest risk of estrogen is to those who have the genetic profile of estrogen sensitive breast cancer in their family, which is true for both sexes... and thus true for those transwomen from those families. The next greatest risk is of blood clots leading to vascular events. A recent paper showed them to be elevated, but no more so than for healthy women taking birth control. Chose your risks... but realize that an elevated risk of a low risk event is still a low risk event.
Am I an endocrinologist? No. However, not only have I been researching the science papers regarding trans issues (all of them) for decades. My college roommate was likely the first U.S. post-op transwoman to have gone to medical school (Stanford class of '85) post-transition then opened her own private primary care practice in LGBT medicine with the largest trans patient list in the country. (It was called the Sea Horse Medical Clinic and was located in Silicon Valley California). So SHE was the transgender endocrinologist (not board certified as there is no certifying board for transgender specialty... but she is The Expert if anyone ever was). She was a member of HBIGDA / WPATH of course. My own education included a focus on biology and psychology (among a couple other unrelated subjects of which I'm considered a world class expert). Anyways... Dr. Shaffer and I had MANY deep discussions regarding the science of transgender medicine and I even worked with her on several of her research projects over the decades.
As for HRT for older women being cut off... yeah... that's silly. Seriously. The studies show mixed results. Frankly, the studies were difficult to interpret because they lumped ALL HRT as the same when we have very good reason to believe that some treatments are very different than others. For example, conjugated estrogens (Premarin) do not have the same effect as Estradiol... and don't get me started on the fact that some of these studies from decades past were with DES! Many of the HRT protocols included using a mixture of an estrogen with a synthetic progestin like MPA... Ummmm.... yeah about that... MPA is a very effect birth control agent but it also has the neurological side effects such as drastically reducing libido in both men and women (in fact, its used as a chemical castration on sex offenders) and reduces the neuroprotective effect of endogenous progesterone in the brain (that is to say... that brain cells will die !).
Another problem with the studies is that they focused on determining the health benefits vs. risks using indicators that have nearly nothing to do with HRT use. For example, they focused on heart attacks in one of the largest studies but ignored quality of life.
The upshot is that many studies in women that lead to the current "wisdom" that women shouldn't be on HRT for very long is from a mix of bad HRT protocols and from bad study metrics. More recent studies focused on quality of life suggest that HRT using estradiol and micronized progesterone may be safer (never none zero risk) and provide better quality of life for many women.
Oh... and other risk factor differences between transwomen and the majority of women... no possibility of exacerbating endometriosis, ovarian problems, etc.
In the final analysis, using modern HRT protocol of Estradiol and Micronized Progesterone (twice daily) does have risks... but not great ones (taking paracetmol / tylenol has risks too....) and the benefits for both woman and transwomen (each for their own reasons) may (and often do) outweigh those risks.