How true is it that lots of lonely people look perfectly fine and you can't tell?

I ask because in my head I think its blatantly obvious that I am myself but maybe others from the outside can't tell. Thats what I like to think because I've been trying to figure out why nobody cares and asks if I'm ok and maybe they simply think I'm fine. Its crazy to think I'm that person that you don't know what they're going through because I don't think I have a mask on.