£500M for a stadium naming rights deal for 20 years is not in the realms of impossibility. £25m per year for a PL stadium of a team in the CL 50% of the time (which you think would increase with more investment), that hosts 30 non-football events (World Title Boxing fights, massive music concerts, NFL games etc.). Really surprised the club were not able to find a sponsor before and that Levy has allowed us to go 5 years without that income stream.
Because the stadium is called Tottenham Hotspur stadium when events held there are broadcast around the world - whether Beyonce concerts, boxing, NFL matches etc, we get the money in different ways via bigger sponsorships, tv rights etc
Become Apple stadium or whatever else, and other income streams reduce - don't fall into the trap of thinking a stadium sponsorship deal is extra money because its not.