Cannot use v-for on stateful component root element because it renders multiple elements?

Your template has to have one root element. It’s just one rule you cannot break. Since you’re making a table, it would make sense to make tbody the root element.

var Users = {
    template: `
        <tbody>
            <tr v-for="list in UsersData">
                <th>{{ list.idx }}</th>
                <td>{{ list.id }}</td>
            </tr>
        </tbody>
    `,
    data: function () {
        return {
            UsersData //get data from query
        }
    }
}

index.blade.php

@extends('layout')
@section('content')
<table>
    <thead>
        <tr>
            <th>IDX</th>
            <th>ID</th>
        </tr>
    </thead>
    <users></users>
</table>
@endsection