On top of this, the criticism from reddit is mostly unfounded and suggests they didn't even bother to read the company's landing page. Multiple redditors say things like "I'd never pay fifty dollars to refer a colleague. What's in it for me?" The landing page clearly states you double your money if they get hired.
Another complaint is that it's racist because black people have black friends and apparently black people can't afford to refer their friends. This complaint relies on a racist argument "black people in general have less money, therefore the black software engineers doing the referrals will have less money." I don't think that's how it works. In the company's model you'd need referrals not from your random friends and acquaintances, but from coworkers who knew you and would be willing to be on you. Presumably your coworkers can come up with fifty dollars.
I think this is a poor idea because it would be awkward to bet on people like this. I'd have to tell my colleagues I didn't think they were good enough to bet on, or bet the minimum, or would I get mad at them if they blew an interview? It's not a good system, but the idea that referrals are broken because they cost nothing to give seems right and it's worthwhile to try and fix important things that are broken.