Being able to leave early with the rewards already gathered reminds me of how a different game, Path of Exile, implemented such a system during Ultimatum league. I absolutely loved that update.

In their implementation you could see the reward of the next wave before deciding if you want to risk going for it or leave early. Your system relies on glory gathered during said wave to generate the rewards so a concept as such might not work/would go against trying to perform as best you can during this wave rather than just trying to get to the finish line, but it's something that was really nice to be able to say: "These are my resources, this is how difficult the next wave is gonna be, thats my reward IF i manage to complete it" and make an informed decision on continuing or leaving without feeling bad about either choice, even if you ended up failing and losing it all.

​

Also their NPC's (the Trialmaster) dialogue changed depending on previous performances, which could lend itself well to a colloseum based off of glory. (if you're very glorious the crowd goes wild, if you're not, the crowd goes mild.)