I kinda agree stepping stone isn't the right term.
For me it would be more wanting to move up to something that is more full size car like.
Its pretty simple, if your lucky you can afford to race something you really want, and have a place to race it. Or if you just gotta race and cant afford your dream ride you find something else to race. Most little guys don't care much about the purse because basically they all suck in the little leagues when you compare to your money commitment. Financially your going to bleed money everywhere. Theres only one winners share and most guys will never see it.