I am not sure if the money really worths it. I mean they could have gotten some other players for that much bag don't you think? It looks like they are going to be pretty cash strapped if they end up putting it on all one player. They will of course be fine, but they won't be able to do any more transfers or at least not big names at all.
Considering all the jokes were about their defense, mainly maguire, last year then it should be clear that they should have considered spending some of that money on buying a defender as well and if they spend this much on De Jong, they can't get a big name to defense at all, hence why it will still be a problem.
In my opinion, there are several options that could be worth it or not from the figure of De Jong with a very high price clause. maybe the first thing we can see is that he is still very young, of course he will be able to play for a long time in the manchester united squad for next season or the following season. Manchester United also learned from what they did when they bought Pogba from Juventus and maybe they won't think too much about the price that Barcelona wants. The current dilemma is whether Barcelona have agreed to the offer made by Manchester United.