hrt needs monitoring. so long as your hormones are kept within normal levels for one of the sexes, there shouldn't be more risk than what's normal for the gender whose normals you're within.
hrt can be very risky if you try doing it yourself. there is also a problem with taking it in pill form (can damage the liver), or self injecting if you don't know how to do it right.
for female bodied persons who decide to keep their internal organs, there isn't sufficient evidence of whether or not stopping the cycle with opposite sex hormones will increase the risk of disease in the uterus. so it is recommended to get checked every once in a while.
there is a possibility that wrong hormone levels can increase anxiety and depression. if the body is unable to produce the right levels (by having gonads of the wrong sex), hrt can actually lessen the risk of some types of accidents. my own view is that anything that makes you feel good about yourself is likely to be good for you, especially if the body doesn't react negatively to it.
i have heard stories about hrt stopping migraines, anxiety, muscle pain, other problems, and making people happier than they could be without. a slightly increased risk of heart disease is easily fought by working out more and changing one's diet. ad it's not like opposite sex hormones is the worst thing a person can take, treating a condition with the wrong same sex hormones can be just as bad, if not worse. "the pill" is one example of a medicament that gives a very high risk of blood clots. a female bodies person could just as well take opposite sex hormones, that might even be safer for all we know.
ad just to add something at the end. vitamin d is also a hormone. we're usually told to take supplements if we have too low levels of this hormone, as it is just as risky to have too little of it. having too little sex hormones is also risky, very risky, so... whatever works to get a person's mental or physical health better will be the best choice. it hrt is what it takes to get someone out of their house and start socializing and working out, then that is much less risky than not getting it.