This is definitely true if “it’s processes are simple” is a requirement for the longtermist organization in question. Influencing the far future is extremely difficult, and can’t even remotely be called a simple process. There definitely are longtermist organizations that have a lot of room for funding and spend their money effectively, though.
I don’t think there is one
I think I’d like some reasons why you think this. Because it’s a very easy thing to think and it could well be wrong.
This is definitely true if “it’s processes are simple” is a requirement for the longtermist organization in question. Influencing the far future is extremely difficult, and can’t even remotely be called a simple process. There definitely are longtermist organizations that have a lot of room for funding and spend their money effectively, though.