I should have qualified my statement a bit more. You are correct that mathematically you can't run it to infinity with these particular numbers. In this case your assets might yield ~120-180k a year, without harming the principal (conservative 2-3% yearly withdrawal). They'd need to 4x their nest egg to actually do it (which they might be able to do), or cut spend.
Having ~180k a year guaranteed budget is a huge operational shift though, as it can change your mindset from short term survival thinking to longer term thinking and free you up to take more risks to help promote and grow the club/sport without fear of folding.
Lots of nonprofit organizations operate this way, with dedicated staff to court large donations. Most high end humane societies, for example, have one time donations make up a serious chunk of their operating income on the year.
All this to say, I hope elite clubs & RTCs can figure out a way to get some big donors in the door, as I think it could help unlock the sport a bit more.