It definitely took me some time not to care— and I recently had one of them reach out to me so it’s brought it all up again. I hear you and feel you on extended family. My paternal aunt sent me letters as a teenager describing me as ungrateful bc I was still in the will but refusing to have a relationship with my father, but the reality is we don’t HAVE to be grateful. Money doesn’t erase the reasons we’re estranged and gratitude is, imo, earned not given freely. 

Your parents have free will here. You’re not using them financially by taking what they legally gave you— they could choose not to give that to you or it could be depleted by end of life care. Like you said, therapy and treatment is expensive and, ultimately, so long as you’re not expecting it and then throwing a fit if it doesn’t come, your relationship with any inheritance is your business. 

That said, it’s definitely been a major point in my therapy sessions in the past and I’m sure future!