Welcome, there can be a variety of reasons. So often a parent will say “I only want you and no one else” and try to get promises that children will “never put me in a home” thinking only of themselves. No consideration whatsoever of the impact on their child!! In fact, the more help they have the longer they can stay home. I just wish our parents had considered what they were doing to us. My husband died at 58 from a massive heart attack, I had a life changing illness at 52. My husband said sadly a few months before he died “You know where we went wrong?”. “Buying a house too near our parents”.
We don’t know your friend’s caring situation (i.e. who she cares for or what disability her caree has) but in my case it took someone else to point out that if I collapsed through trying to do everything without outside help (either the formal assistance of carers of the informal assistance of friends and/or family) then I would be in no fit state to care for my Mum.
If you are on aeroplane that is about to crash you are always told to put your own oxygen mask on first before helping those around you with theirs - same thing with caring, looking after your own health and welfare is paramount if you want to continue caring.
It’s not a sign of weakness to ask for help - personally I see it as a strength to be able to admit that for you to do the best you can you need the support of others.