Agreed. These people see battle rap has a strong fan base and think it's a quick lick and try to throw cards but there's various factors they keep forgetting
1) Battle rap is still niche, so even though there's a strong fan base and a lot of popular people who watch, it's still not a LOT
2) Low key we're in a recession, people don't really have extra money to be spending on shyt like battle rap tickets or battle rap PPVs
3) You're probably gonna see a loss for the first 3-5 years of any business venture. You need a shyt ton of capital to maintain through those years of brand building
Like you said, the best method to starting a league is build up your own guys. Sure you can outsource a few URL battlers who are on the lower end but have a name, a few guys who are formerly associated with the brand, or guys who don't get booked often and aren't under contract. All start ups need familiar faces to get new fans engaged. But ultimately the backbone of your league should be your own guys.