Good for you that you have an exit strategy for when you are ready to leave escorting, and you make excellent points about the risks in other professions, but that's life, there is no way to know what circumstances are just around the corner. The balance is that, while some people are defeated by stress, others thrive on it.
My condolences for the loss of your friends. I can understand your feelings, but I don't believe you should live your life dwelling on the possibility that because your friends passed at young ages that you will also.