In the old joke, a college president complains to his physics professors that they are always asking for expensive equipment. All the mathematics teachers need is pencil, paper, a wastebasket, he says, and the philosophers don't even need the wastebasket.
There has always been a feeling among many that philosophy is useless or worse, and one can find this sentiment expressed not only by Aristophanes, for example, but by several interlocutors in the Platonic dialogues. In "Thesis on Feuerbach," Marx famously complained that heretofore philosophy has only described the world, when the point is to change it.
Philosophy, after all, does not put food on the table, win battles, or construct machines. As others here have noted, philosophy did engender many academic disciplines, from physics and psychology to sociology, computer science, and modern economics.
But once these fields became mathematically formalized for control and prediction, in other words "useful," they were no longer part of "philosophy." Of course, the very idea that "physics is more useful than philosophy" is itself a philosophical assertion, not something you can prove within physics.
There is something about philosophy that is inimical to practical applications. One could think of it like art as an end in itself not a means. Once the argument becomes a "means to an end" it is no longer philosophy. Science, for example, is means to the end of understanding causes for purposes of prediction. But it is engineering that turns this into "useful" things, not the science per se.
Since philosophy considers all assumptions to be fair game for critique, it cannot arrive at the sorts of axioms that make science "work" and its findings transformable into technologies. That conditional "suspension of falsification" in the "working theory" defines a "cause" but not the cause of the cause, the infinite regress of "because" that compels philosophy.
Since Socrates, philosophy has been a kind of via negativa revealing what we don't know. Yet, this is useful, many would argue! It is a method of revealing our false assumptions and vast complexes or shaky beliefs. As Mary Midgley notes, philosophy is everywhere and a bit like plumbing. You just don't notice it or think you need it... until the assumptions start to break down.