Compared to Grand Theft Auto that's low.
50-100 million is honestly a mid tier AAA title, if you want the best you have to pay through the nose. That's how much a real AAA game truly costs, and you can see where the money went for Deus Ex Mankind Divided, buckets upon buckets of level designers.
It's all relative to what they have the potential to sell though. Deus Ex isn't GTA so it can't get away with a budget of that size.