It's pretty typical, actually. 50% is about the minimum that major universities take out of a grant you get as a researcher at the university.
It's nominally to fund general facilities, etc. At least at public universities, it does wind up indirectly supporting departments that get less grant money or (more commonly) just general overhead/funds. However, it's not explicitly for that. It's just that universities take at least half of any grant you get. There's a reason large research programs are pushed for at both private and public universities. They do bring in a lot of cash that can go to a lot of things.
This also factors a lot into postdocs vs grad students. In addition to the ~50% that the university takes, you then need to pay your grad student's tuition out of the grant. At some universities, that will be the full, out-of-state/unsupported rate. At others, it will be the minimum in-state rate. Then you also pay a grad student's (meager) salary out of the grant. However, for a post-doc, you only pay their (less meager, but still not great) salary. So you get a lot more bang for your buck out of post-docs than grad students, for better or worse. This has led to ~10 years of post-doc positions being pretty typical post PhD in a lot of fields.
With all that said, I know it sounds "greedy", but universities really do provide a lot that it's reasonable to take large portions of grants for. ~50% has always seemed high to me, but I do feel that the institution and facilities really provide value. E.g. things like "oh, hey, my fancy instrument needs a chilled water supply and the university has that in-place", as well as less tangible things like "large concentration of unique skillsets". I'm not sure it justifies 50% grant overhead, but before folks get out their pitchforks, universities really do provide a lot of value for that percentage of grant money they're taking.
It's nominally to fund general facilities, etc. At least at public universities, it does wind up indirectly supporting departments that get less grant money or (more commonly) just general overhead/funds. However, it's not explicitly for that. It's just that universities take at least half of any grant you get. There's a reason large research programs are pushed for at both private and public universities. They do bring in a lot of cash that can go to a lot of things.
This also factors a lot into postdocs vs grad students. In addition to the ~50% that the university takes, you then need to pay your grad student's tuition out of the grant. At some universities, that will be the full, out-of-state/unsupported rate. At others, it will be the minimum in-state rate. Then you also pay a grad student's (meager) salary out of the grant. However, for a post-doc, you only pay their (less meager, but still not great) salary. So you get a lot more bang for your buck out of post-docs than grad students, for better or worse. This has led to ~10 years of post-doc positions being pretty typical post PhD in a lot of fields.
With all that said, I know it sounds "greedy", but universities really do provide a lot that it's reasonable to take large portions of grants for. ~50% has always seemed high to me, but I do feel that the institution and facilities really provide value. E.g. things like "oh, hey, my fancy instrument needs a chilled water supply and the university has that in-place", as well as less tangible things like "large concentration of unique skillsets". I'm not sure it justifies 50% grant overhead, but before folks get out their pitchforks, universities really do provide a lot of value for that percentage of grant money they're taking.