At 200 dollars a week, it will take 10 years to pay off the debt. What gangster would allow anyone that amount of time? So unless she starts earning considerably more, like thousands of dollars a week, then there's no way they'll stay alive long enough to pay it off. I mean we're already suspending disbelief, because the whole idea of a 200 dollar a week repayment scheme for a 100k debt to a ruthless gangster, is already beggaring belief. It would never happen in the real world, and Mike would already be dead in a ditch.
The real reason behind the 200 dollar a week repayment scheme, is the Dev wants this to be a slowburn corruption of Riley, and therefore she has to be able to have relatively tame jobs at the start of the game, which naturally don't pay as much. Rather than fast-tracking her into becoming a complete slut, so she can earn considerably more as a cam star, stripper or escort, and thus would be able to pay back, far more than 200 dollars a week. If she was really desperate, and was convinced that Wyatt would murder her and Mike, if she didn't pay back much more each week. She wouldn't even think twice about doing whatever it took to earn that money. She might hate herself, but she'd still do it. But because the Dev has decided this game is going to be a slowburner, instead we have this ludicrous scenario which totally stretches credibility.
Rather than just getting a loan, they could have had Mike laundering money for the Mob, until he could repay them what he owned. That would be more realistic, because then they're getting a significant benefit from the arrangement, rather than just a tiny pittance, which wouldn't even cover the high level of interest that they would naturally expect on such a sum. Because when you add in interest, Riley would likely be paying 200 dollars for the rest of her life, if her repayments remained at that level. Having Mike be involved in some criminality under duress, would also provide Riley with a big incentive to pay back the money as soon as possible. It provides a much more logical reason, for her eventually succumbing to corruption, regardless of whether Mike is a cuck or not.