Of course, this is completely pointless, as no football club can spend over what they earn and Newcastle (/all clubs) are only as rich as their revenue.
The last time I can see any stats about Newcastle’s revenue was from 2018-19 when they earnt £182m (compared to City’s £540m).
Also, owners only put initial outlays into clubs and then aim for the club to be self sufficient. So the most important thing is how well a club is run, not how much money their owner is worth.
No owner is going (or even can) just put hundreds of millions into a club every season. FFP won’t let them anyway but, even if football was run like any fair business was, an owner might do that for a few years but then will want to see the club stand on its own two feet and use it’s own revenue to move forward.
That’s why Brentford are in the Prem despite being run on a low budget and QPR, who have the fourth biggest consortium behind them in the country, are nowhere and are doing nothing. QPR either aren’t run well enough, or they can’t spend enough money to push them on because their revenue is too small.
And even if Newcastle do get up to City’s revenue levels in the next 15 years, they’ll still only be able to spend as much as City.