<?php

$data = [
    [
        'id' => 1,
        'users_id' => 100,
        'account' => 9000000
    ],
    [
        'id' => 2,
        'users_id' => 100,
        'account' => 4000000
    ],
    [
        'id' => 3,
        'users_id' => 100,
        'account' => 5000000
    ],
    [
        'id' => 4,
        'users_id' => 200,
        'account' => 1000000
    ],
    [
        'id' => 5,
        'users_id' => 300,
        'account' => 2000000
    ],
];
foreach ($data as $d) {
    $tmp_data[$d['users_id']][] = $d;
}

$result = $tmp_data;

foreach ($data as $d) {
    // cara mengakses yang sudah di indexing by users_id
    var_dump($result[$d['users_id']]);
}