It's very different to PSG.
They don't sell their key players and have effectively made two signings that were well above the previous transfer record. They are a team that has a clear goal of winning the CL.
I honestly don't think that is our main objective. Of course we want to, and we want to build our team to be as good as it can be, but we always have one eye on the balance sheet. Our net spending proves as much over the past few years. Hitting the quarter final is the minimum target we set every year, we say this every season. I think we want to continue to grow financially to build a better team long term. Say what you like about our board but I don't think they are as short sighted to think that adding Higuain suddenly makes us a Champions League winning team. We needed a striker, we had money and Higuain was the best available player within our financial reach (incl wages) to sign, especially whilst weakening a rival.
If your sole aim is to win the Champions League, you do not sell top players every summer.