There are some incredibly naive people on this thread.
There are private Facebook groups dedicated to what to say on PIP forms to ensure a successful claim. Not for disabled people. For people who want PIP as a top-up, and ask for help with providing conditions that they cannot prove.
I'm a disabled wheelchair user. When I applied for PIP, I had zero medical evidence. I suffer with medical trauma and PTSD and avoided healthcare at all costs. I was still awarded PIP, higher rate for both elements.
I'm not sure why people think PIP is hard to get. It used to be slightly harder, but now most assessments are done over the phone, it's even easier to lie, should you so wish to.
A colleague of mine frequently laughs about how she made up depression and back pain and now she has a free car. She finds it hilarious. She keeps a wheelchair in her house in case anyone comes to check (she also claims wheelchair user council tax discount). She does extreme sports, mountain climbing, marathons, etc. People like this exist, and they truly believe that it's OK, because the government is "screwing over" everyone, so they may as well get what they can.
The PIP system is completely broken, and people know it. It's amusing that non-disabled people will argue that it isn't.