试试这个

using System;
using System.Collections.Generic;
using System.Linq;

namespace TestThings
{
    class Program
    {
        static void Main(string[] args)
        {
            List<User> users = new List<User>() {
                new User(){
                    Name = "User1",
                    NetworkRoles = new List<NetworkRole>() {
                        new NetworkRole(){
                            Description = "NetworkRole1",
                            NetworkRolePrivileges = new List<NetworkRolePrivilege>() {
                            new NetworkRolePrivilege(){
                                Description = "NetworkRolePrivilege1",
                                UserPrivilege = new UserPrivilege(){
                                    Description = "NetworkRolePrivilege",
                                    Enabled = false
                                }
                            }
                        }
                        }
                    }
                },
                 new User(){
                    Name = "User2",
                    NetworkRoles = new List<NetworkRole>() {
                        new NetworkRole(){
                            Description = "NetworkRole2",
                            NetworkRolePrivileges = new List<NetworkRolePrivilege>() {
                            new NetworkRolePrivilege(){
                                Description = "NetworkRolePrivilege2",
                                UserPrivilege = new UserPrivilege(){
                                    Description = "NetworkRolePrivilege3",
                                    Enabled = true
                                }
                            }
                        }
                        }
                    }
                }
            };

            var _users = users.Where(u=> u.NetworkRoles.SelectMany(x=>x.NetworkRolePrivileges).Where(x=>x.UserPrivilege.Enabled).Any()).ToList();

            foreach(var u in _users)
            {
                Console.WriteLine(u.Name);
            }

            Console.ReadKey();
        }
    }

    class User
    {
        public string Name { get; set; }
        public ICollection<NetworkRole> NetworkRoles { get; set; } = new List<NetworkRole>();
    }

    class NetworkRole
    {
        public string Description { get; set; }
        public ICollection<NetworkRolePrivilege> NetworkRolePrivileges { get; set; }
    }

    class NetworkRolePrivilege
    {
        public string Description { get; set; }
        public UserPrivilege UserPrivilege { get; set; }
    }
    class UserPrivilege
    {
        public string Description { get; set; }
        public bool Enabled { get; set; }
    }
}