Tourism?
I've been to Vegas twice before the Knights showed up. Them having three sports teams would definitely motivate me to go even more. And unlike other cities, it's already a tourist haven, just gives a little incentive for fans to plan a trip. I've noticed the Raiders games have about half of the crowd wearing their opponent's jersey. Whether that's enough, time will tell.
Why do folks come to Las Vegas? Conventions is one big driver....
"With more than 10.5 million square feet of convention and meeting space (most in the U.S.), Las Vegas hosts
nearly 60 of the 200 largest conventions (most in the U.S.) and 20,000 meetings annually (most in the U.S.)."
Adding on a sports game as evening entertainment in conjunction is quite possible. (Or one of dozens of evening entertainment options, from 6 Cirque Du Soleil shows and many other options from magic to music options in just about every genre. About three dozen museum options too. Not to mention the types of "entertainment" that historically most folks think of as Vegas.)
150,857 hotel rooms as of 2022 (with a couple more resorts coming on line soon). (There are more hotel rooms on one intersection than all of San Francisco.)
Team sports:
NHL, NFL, future MLB only? NBA Summer League? What about WNBA and G League? USL? MiLB? IFL? XFL? NLL? (Heck, there's even a roller derby team) And multiple developers trying to lure the NBA to have expansion team in town.
What about NASCAR, F1, drag racing? Not to mention off road racing (e.g., Mint 300).
Golf? Including PGA tournament (Shriner's Children). "There are
39 golf courses in Las Vegas, Nevada and 3 are municipal courses. There are also another 19 golf courses within 20 miles of Las Vegas, including 9 public, 3 municipal and 7 private courses. "
Tournaments including tennis?
Equestrian events? NFR? Bull riding?
No reason to be bored in Vegas.