Well, I don't think anyone gets that much on PIP but people certainly do get PIP for anxiety, there's a success rate of 45% for anxiety claims.
No shade on the OP as he quite clearly had a serious medical issues but there are likely plenty and there's lots of advice out there to help fill out the forms and say the right things in interviews too:
Charlotte Anderson, from Staffordshire, is helping people secure a disability allowence by offering advice on YouTube and charging up to £650 for a one-to-one meeting
www.mirror.co.uk
No one assessing people for PIP knows how the person making the claim feels inside and having a given diagnosis or several of them doesn't necessarily mean claiming PIP as some of those people don't struggle with daily tasks. Lots of that is self-declared and based on the form filling and what is said in interviews etc. thus you can have someone who knows the system well basically guide you through a claim.
One small example I've seen cited a few times is they might have an appointment in an office up some stairs, someone who has been coached might know not to climb the stairs and make a fuss about that etc. not because they couldn't actually do so but because it looks better for their claim. And of course, they'll be told what to say on all the forms to ensure the best result from whoever is going through a box-ticking exercise when reading it (and of course if that person messes it up then -> appeal and have someone else do the box-ticking exercise on the form that has been specifically tailored to tick the right boxes/score enough points).