Just because you have more money it shouldn't necessitate spending more money. In fact, that's why English clubs have not progressed in Europe for years now or closed the gap on the footballing elite, all of whom are spending shrewder and smarter than 'we' are.
This newfound money is supposed to flood the global market and destablise these top clubs as new players(clubs) in said market are ready to go toe-to-toe with them for new players or even their own via what-can-then-be incredible financial offers.
The English teams could have made big waves with the money, but have instead shafted themselves and made themselves prey to any potential suitor.
As a selling club, of course Spurs have themselves an incredulous deal. It's the buying club who are having a mare here.
We can say 'it's City, they don't care.' but the knock-on effect is going to hit all clubs in the league, just as it will with Lukaku going for so much and thus setting a precedent.
Of course, many saw this coming and said Pogba will look a steal within the next few years, but there has been a leap in just a couple of windows that few would've foresaw and now we have players like Walker being sold for £50m just a year later. By that token, Pogba has to be a £150m already... just a season later. Madness.