Let me preface this, unless it's a kids' birthday wish, I'm not willingly going there.
Youtube channel did an ingredient comparison, and while they are quite expensive, McDonalds if fucking you over way more.
https://www.youtube.com/watch?v=5zOmh9F4xcs
TL;DW, it comes down to meat. Using grocery store ingredients, they made faithful comparisons to fiveguys, in and out, and McD.
The hamburger is by far the most expensive part and fiveguys does actually use more than the rest.
McDonalds big mac had 107% markup.
In and out Double, had 44% markup
The 5 guys regular burger was 84% markup
It cost them over $8 to copycat Fiveguys.
That said, a meal for 4 being over $100, we better be eating something fancier than fast food.