Barcelona was built on La Masia earlier in the century. They need to return to that. Puyol, Xavi, Fabregas, Iniesta, Messi, Valdes, Pique all were around the same generation and then you add in people like Busquets, Alba, Pedro and that was how the team was built. You didn't need big signings because your stars were internal (even if Fabregas, Pique, Alba left).
Then they started signing players. Neymar was fine, but set the trend. Coutinho, Dembele, De Jong, Greizmann, Pjanic, etc. They bought into the arms race when they had been developing just fine.
Luckily they have some solid talent coming out of La Masia still (Fati, Moriba, Puig, Collado, Mingueza, Gavi) but they need to commit to it again and then buy sparingly. Of course, it looks like they're trying to get rid of Moriba (which is understandable) and maybe Collado as well as selling Trincao