Updated August 1, 2023
Some people like to walk and though it's not a frequently asked question, we've fielded at least one query about it.
Assuming luggage isn't an issue (for example, an inveterate backpacker carries everything on his or her back), the challenge isn't so much the distance from the airport to the Strip. According to Google maps, it's only 2.5 miles from Terminal 1 to Excalibur (add a half-mile from Terminal 3). Google suggests 51 minutes, which is a typical 20-minute mile; your mileage might vary, depending on your own pace and, again, the weight you're hefting.
The problem is more that the airport is designed for anything but walking to and from. The sidewalks peter out at the end of the main terminal building and then you've got more than a half-mile of lane crossings, overpasses, and general heavy Las Vegas traffic -- lead-foot cab and Uber/Lyft drivers, buses and shuttles, limousines, visitors in rental cars, locals picking up and dropping off, all jockeying for position, with a luggage-toting pedestrian on the thoroughfares the farthest thing from their minds.
Not that it can't be done, of course. In our many many trips to and from the airport, we have seen pedestrians on foot wheeling suitcases, though admittedly it was on rare occasions and they looked a little bewildered.
As always when hoofing it around traffic, if you're especially cautious and patient, you'll probably make it. (A good idea, however, might to be make sure your life insurance is paid up. And you can't go wrong wearing high-visibility safety apparel.)
So you follow the one-way traffic past the terminal building and out onto Wayne Newton Boulevard for approximately four-tenths of a mile. The most dangerous part is where Wayne Newton crosses over Paradise Road; there's no shoulder and you're jammed in between the guard rail and the traffic. But once you're on the other side, you join up with Swenson Street, which has a nice wide sidewalk and you're pretty much home free.
You can continue north on Swenson till you hit E. Tropicana or you can cut west on one of the cross streets; you'll pick up Paradise Road (heading against traffic), where you take a right to head north again to E. Tropicana. In total, it's roughly a mile from Terminal 1 to E. Tropicana.
From the intersection of Swenson, it's 1.5 miles to the Strip. From the intersection of Paradise, it's 1.3 miles to the Strip.
It's more likely, of course, that someone might need to walk from the Strip to the airport -- after losing all their money and not having any left over to pay for an Uber or shuttle.