I'm not arguing he's a good guy or anything (I mean, look at him here)
But if the question is what is the source of the wealth being used to finance Newcastle, the answer is simple: oil.
What is the source of the wealth used to finance Chelsea by Roman? Proceeds from wealth derived from assets violently/illegally acquired by Roman for cheap through personal connections in the chaos that was post-Soviet Russia created in part by shock therapy advised by the West who were more concerned about Russia being capitalist than Russia being democratic
What is the source of the wealth used to finance City and PSG? Oil.
See the difference?