If they make a bad product do you want more of it, even for free?
Like, reviewers get to the point where companies send them free product for review from a long period of legitimate reviews that get them a large enough audience. It's unlikely they're getting their main profits from free products sent.
Obviously you shouldn't take a single person's review as gospel anyway, but just them getting a review copy of a thing isn't a sole reason to discredit their opinion.
Is your family member Google Ad Sense?
"I see you spent a week researching PSUs for your computer and I see that you finally bought one. Would you like to buy a PSU? because even though we know you bought one we'll be showing you nothing but ads for PSUs for the foreseeable future."