Newcastle has never been the same as Chelsea, Manchester United, Arsenal and Manchester City in terms of player transfers. I mean, Newcastle management is more concerned with long-term projects by building squad depth gradually rather than spending a lot of money in one transfer season. This policy can certainly help them save a lot of money on purchasing players, but they also prioritize quality.
Yup, sometimes money doesn't promise that a club can become champion in one season. On the other hand, clubs with players who are not widely known can give amazing results at the end of the season, for example when Leichester won the EPL. Chelsea often spent a lot of money on players, or MU, but they couldn't get the EPL title. The decision to build slowly, creating confidence from players that there is progress from Newcastle and its potential to become a consistent as top tier team will start to get the attention of good players. At that time, negotiations with players will be easier. let say, in condition, if Mbappe have to choose, Mbappe would not choose Newcastle even though he got more money. Because, PSG will have more potential to give it the Ligue 1 title, rather than the potential for Newcastle to win the EPL.