Vegas is growing, again growing in full-time residents and growing in destination for all things sports. UNLV right this moment may not be a big program and people may not be paying attention to them locally, but give them a P5 conference, P5 money, and a big platform and why wouldn't UNLV blossom into a major successful program?
Who would have thought Hockey would work in Las Vegas? Within 10 years the Golden Knights have a stanley cup and there are Golden Knight stuff EVERYWHERE in Vegas. They love the Golden Knights. Once a team becomes successful in LV the locals take to it, hell I was in Vegas before the Knights first season and the city was so excited about them and they had Knight stuff everywhere. Imagine the hype train if their local university was propelled to a P5 conference?
You add in the potential donors/boosters from the casino's and the marketing put out there by the casino's through the use of the UNLV program and suddenly the Rebels have a huge budget.
Utah was a G5 program and came into the Pac12 and grew. Look at Utah now. Colorado was a crappy P5 program who moved to the Pac12 and remained crap. That move from the Big12 to Pac12 for Colorado did nothing for them. Meanwhile, Utah's move from the G5 conference to Pac-12 as propelled them to one of the top and most consistently successful programs in the country. Utah is doing this within Salt Lake City, not Las Vegas.
You're blind if you can't see the huge potential in UNLV in a P5 conference. They may be bad now, with no history of success, but you put someone in there with a vision, who can capitalize off it's location and it's market and this is a program that won't take long to explode into relevancy.