It’s legal because both sides have armies of lawyers and are voluntarily entering into contracts where each party gets consideration.
How someone can compare the above situation to a person getting a payday loan to put a roof over their head or food on their plate is beyond me.
The “it’s like <insert wild and inappropriate analogy to stoke emotion>” is a tired trope.
Come on, calling a round of vendor financing (which is what the NVIDIA money is) "funding" is eggregiously misleading. The only new money entering the sector from this is SoftBank's stake.