@chrystaltree People just don't think about it. My husband and I did this for aunts, uncles and parents from 40 on and are still doing it close to 30 years. But unless you have been there you cannot imagine the work involved, the paper work, reports, medical decisions, floods of paperwork that come to you, etc. etc.
I do not blame the siblings. Some guardian/feduciary/ power of attorney situation needs to be set up, and they do need to get help from knowledgable people. It's almost more than someone can manage at 40 and still have a life, no less at 60.
Been there done it and to be honest it comes before what one needs to do for their own life--you HAVE to do the reports, accounting for all funds, allocations to housing, clothing, etc. for them because govt. agencies are involved. Your life gets pushed back to second or third place.
My husband took the burden. I simply don't think I could have done/do it alone.
Just my experience.