I have read several of these. I love the king of the road fantasy Child sells: observant hyper-physical superman working for justice, with no ties, no fears, and new girl every adventure. James Bond and Travis McGee come close to this fantasy but Jack Reacher is freer from the world than they are. No boss, no best friend, not even a change of clothes. He is an ideal, really, the purest example I know -- almost an abstract extension of 'guy'. It's easy to laugh at him, and perhaps he should lay off the head butting before he ends up with CTE, but I think there is a small yearning towards Reacher in most of us Y-chromosome types.
Know who he reminds me of? Bella, from Twilight. Yup. Now, here I am talking without a lot of knowledge (I've been unable to get through one of the books) but ignorance has never slowed me up before. And I am aware of Bella as an icon. She seems to embody a certain aspect of femininity -- pliant and submissive, seeming to exist only for relationship, succeeding through manipulation. And what a success she is! Not one but two sexy powerful guys will do anything -- anything -- for her. Like Reacher, her girl fantasy is almost perfect. She doesn't even have to walk by herself if there is a guy to carry her. Again, it's easy to laugh. But pay attention to the bit inside that is somehow satisfied by Bella -- or what's her name from 50 Shades, who is virtually the same character.