Since knowing how to make money is worthwhile only to the extent that you know what to do with it, it must be pursued while keeping its goal in mind. King Shlomoh has something to say on the topic:
There is one and there is no second, he has neither son nor brother. But there is no end to all his toil, neither is his eye sated from wealth. And for whom do I toil and deprive myself of good? This is also futile and a bad state of affairs.
The thrust is that money is to be enjoyed, not accumulated; an individual with no dependents or heirs has nothing to work for after satisfying his own needs. This is a jab at one who labors beyond what he needs for himself and his loved ones, thereby limiting his own enjoyment.
Here too, as in the acquisition of wealth, the Rambam advocates moderation in expending wealth. Between the extremes of the miser who would rather starve than spend a penny and the spendthrift who happily wastes everything he has, there is a medium that balances preservation of wealth with enjoyment of it.
What you acquire is not to be taken lightly. The Sages say that the righteous prize their possessions as highly as themselves – or more so – noting Ya’akov Avinu’s crossing the Yabbok River late at night just to retrieve a few small jars he had inadvertently left behind. Tzaddikim are so “materialistic,” as the Talmud explains, because their hands are clean of theft. Conscious of how much effort it took to scrupulously acquire even his cheapest possessions, Ya’akov was willing to put himself in possible danger to avoid losing one of his possessions, rather than just relying on his wealth to buy another one.
The Chafetz Chayyim notes that the Sages forbade all but the extremely wealthy from spending more than one fifth of their possessions on charity. This limit was not instituted to encourage wasting the other four fifths, but to teach a lesson about the importance of spending wisely. If one has to limit one’s spending even for such a worthy purpose, all the more so must one limit it on purchasing nonsense.
 Kohelet 4:8.
 Hilchot Deot 1:1.
 Chullin 91a.
 Ahavat Chesed, part 2, 20:5.