It is possible to construct a worldview under which everyone else is benefiting from the work that Slytherins (and Hufflepuffs with sufficiently narrow circles of concern) do.
It takes a lot of amoral sons of bitches to keep everyone else from getting eaten alive. And it takes even more amoral sons of bitches to plunder enough loot to keep their society sufficiently affluent to support Gryffindors and Ravenclaws, and fight off the other societies that would like to have that loot but maybe wouldn’t have as many Gryffindors or Ravenclaws, at least not of the kind we like.
It is possible to construct a worldview under which everyone else is benefiting from the work that Slytherins (and Hufflepuffs with sufficiently narrow circles of concern) do.
It takes a lot of amoral sons of bitches to keep everyone else from getting eaten alive. And it takes even more amoral sons of bitches to plunder enough loot to keep their society sufficiently affluent to support Gryffindors and Ravenclaws, and fight off the other societies that would like to have that loot but maybe wouldn’t have as many Gryffindors or Ravenclaws, at least not of the kind we like.