If it's too good to be true, it usually is.
In regards to SEO, it helps you.
In reality, you run a big risk of likely wasting your money and getting no SEO.
Does the competitor know you? Do you have great communication with them? Do you trust them not to sabotage the paid hardlink via noindex in robot.txt or nofollow ?
If you have a good working relationship with your competitor, and you trust them, then hopefully you'll get what you paid for and they won't sabotage your paid hardlink
