I run a blog and use Amazon affiliate program on the blog and earn $3,000.00 per month and even make commissions on sales of things that I was not promoting.
That's the good thing about Amazon affiliate program as you can promote things you're interested in and make a commission on those items.
But also if the person who clicks on your amazon affiliate link or amazon Affiliate ads makes other purchases after using your link then you get commissions for those items as well.
So the more the person buys the more money you make from Amazon affiliates as well.