Sorry but this is extremely naive and overly simplistic. In 'real life', trophies are actually pretty much irrelevant for the vast majority of clubs, so it might be more wise to say that the primary sports-related* goal for any club is to
exceed it's expectations of footballing success over the medium to long term (or at least something like that).
Why do I say 'exceed expectations' rather than 'win trophies'? Well, surely the sports-related target of the management should be to do better than expected, or maybe better than resources would suggest is possible. Hence if Man City win the PL this season and Luton finish 2nd, surely we'd all agree that Luton deserve more congratulations than Man City, they would have had more relative 'success' when you factor in the context. Well that's the way I see it anyway - you're welcome to disagree and say that you'd think City more deserving of praise in that scenario if you wish, that's your prerogative - but I suspect most would say Luton had been more successful there.
Why do I say 'medium to long term'? Well, any team with a bit of good form and/or good luck can have a good season or a good cup run - a bit like with investing, there will always be short-term ups and downs - but it doesn't really make sense to judge the management's overall tenure on a single season.
What's my point here? Well, Levy will be trying to balance financial success with footballing success. He may not always do it well, but that is surely what he will be trying to do. Hence, going back to the origin of this conversation, he will naturally want to get good value for money when buying players, as would any business buying any asset. Yes you might sometimes pay over the market price, but only if you were confident that the asset would have some attribute that you could exploit better than others, thereby still making it good value
for you. If it was only about 'winning trophies' - i.e. if money was irrelevant - then yes he should spend £500m on the best player - but money isn't irrelevant, it is both relevant and finite, so Levy will do whatever he thinks right in terms of investing in the football side at a level he believes will also ultimately benefit the business side. Does he always get that right? Of course not, no one does - but that is what he will always be trying to do, and should be trying to do.
So for me, even we do buy a player for £150m, we should only be doing so if we consider that to be 'good value' for us.
Side-note:
* I say 'sports-related' as, whether you or other football romantics like it or not, football clubs are businesses, and for many of them, the owners if they are honest are more interested in growing the value of their asset than footballing success. Now of course the latter may assist the former, but that's not the point - the point is that owners might well consider asset value as more important than footballing success, and it would be wise for fans to remember that. This of course is the owners' right - contrary to what many fans seem to think, the owners by definition own the club as an asset, hence within reason and law, they can run it however they wish, focus on whatever they want etc. That is their right earned by achieving sufficient wealth to purchase the asset. If you have or save up enough money, you can do the same.