Betting currency is a terrible solution, especially at the junior level when people are trying to start their careers. On the other hand, forcing candidates to invest time and in exchange guaranteeing their application will be reviewed could work well.

Candidates aren’t going to apply until you can actually guarantee that their application will be reviewed and given due consideration. And that will never happen because the fakers will invest an unlimited amount of time, so your review process will fall over.

Huh? The problem is getting to the point where the company is able to have a candidate invest time and then review their work. If the candidate doesn't have the application fee, there could be a secondary market of people who would back the candidate if they were confident they could get the job and the escrowed application fees.

"Hey, if you want to work, pay us" sounds so fucking dystopian.

I already saw "work" offers where YOU have to pay them their salary. As in, to employer, for the "opportunity"

Idea 3: Use a prediction market to find the best candidate.