Fortunately for me, I'm a Wednesdayite so I get to eat nice food instead of greasy chip butties!

but as the sole ingredient in a sandwich????? Then again, I am a Pittsburgh area guy and we had the Primanti brothers sandwich - fries, slaws and meat stacked up

That finds me perplexed as to why?

Fills up your stomach and soaks up all the beer you've consumed on a night out.

You can eat chips a lot faster in a chip butty than with your fingers.

For a proper chip butty, the bread's got to be buttered well, slathered on, so it makes a sort of sauce and lubricates the starch on the way down. Add salt and maybe vinegar (ketchup if you're feeling fancy), and with decent chips (US fries, though UK crisps - US chips - work, too for a low-cal option), it can be a real treat (I haven't had one in years, but my tummy's rumbling now).

Used to occasionally get a takeaway lunch in Dumbarton quite a few years ago. This cafe on the high street had a queue of schoolkids out the door. Their specialty was a "hauf V 'n' chips" - half a well-fired Vienna loaf, split lengthways, buttered and filled with chips. By gum, it took some eating.

That would at least add some protein.

A chip butty is a sandwich made with chips (i.e., French fried potatoes) on buttered white bread or a bread roll, often with an added condiment such as ketchup, brown sauce, mayonnaise, or malt vinegar.

The chip butty can be found in fish and chip shops and other casual dining establishments in the United Kingdom.
It is also less commonly known as a chip sandwich, chip batch, chip roll, chip muffin, piece and chips, chip piece, or chip sarnie.

One variation is the chip bap or chip barm, which uses a floury bap or barm cake instead of sliced white bread.
In the East Midlands a chip butty made with a bread roll is referred to as a chip cob.

A chip butty can be vegetarian if the chips are not fried in lard or dripping.

https://en.wikipedia.org/wiki/Chip_butty

Where I'm from they are breadcakes. To people in Derby & Nottingham they are cobs, in West Yorkshire they are teacakes (teacakes are something very different in my book), Southerners call them rolls, and they are also known in other parts of the country as barmcakes, baps, stotties and a number of other terms.

People will get on their high horses about this as well, so you can get people who insist that they are teacakes or rolls and get very annoyed by all the other regional terms for breadcakes!

I'm actually partial to chips with mushy peas on top or a bacon butty.