I am trying to echo an image to the background like so

$product_pic = get_the_post_thumbnail($pid, 'full');
$pid = $result[0]->productID;

<style>
    .product-pic-bg{background-image:url("<?php echo  $product_pic;?>")}
</style>

It doesn’t work. All I get is .product-pic-bg{url""} in the console.

When I dump the $product-pic I get:

What do I do to get this to work?