id  | name              | cat_parent_id | slug
--- | ------------------| ------------- | -------------
1   | Parent - 1        | NULL          | parent-1
2   | Parent - 2        | NULL          | parent-2
3   | Child-1- P - 1    | 1             | ch-1-p-1
4   | Child-1- P - 2    | 2             | ch-1-p-2
5   | sCh-1-Ch-1-P- 2   | 4             | sch-1-ch-1-p-2

public function children()
{
  return $this->hasMany('kblinkedCategory', 'cat_parent_id', 'id');
}

public function category(Category $category)
{
    $categories = $category->first()->children;

    return view('product.list', compact('categories'));
}

Route::get('/{category?}','ProductController@category');

public function children()
{
  return $this->hasMany('kblinkedCategory', 'cat_parent_id');
}

public function category($category) // $category is id of category
{
    $category = Category::findOrFail($category);

    return view('product.list', compact('categories'));
}

@foreach($category->children as $child)
  {{$child->name}}
@endforeach

Route::get('{category1}/{category2?}/{category3?}/{category4?}',
    'ProductController@category');

public function category(Category $category1, Category $category2 = null,
        Category $category3 = null, Category $category4 = null) {
    $category = collect(func_get_args())->filter()->last();

    $categories = $category->first()->children;

    return view('product.list', compact('categories'));
}