Current squad is after big spending under Lampard and already existing league and European winners. Its only reinforcement and getting all these dramas behind. May be current dip in form were about the uncertainty of club's future. Next season will be even more tough with Ten Hag's rebuilding, Arteta's progress and Conte's spending etc.
Newcastle's board's/owner's plan/vision is not to make another City (in short term). They Amanda Staveley stated they want to make Magpies title winning team in about 10 years. Also, putting together a group of players costing 3 figures and thinking they will win trophies is not going to work that easily, rather gradual building is the way forward. Howe is going to do this in the interim with may be 100m in summer and see how they go - will be, I think, their current strategy..