It's killed a lot of people.

https://news.northeastern.edu/2024/05/24/uk-contaminated-blood-scandal/

Desperate people sell their blood. They lie about drug use and infections because they need money. High-risk Prisoners had to sell blood at under the going rate, and then this was covered up for profit.

Things have got better with more rigorous testing, but there's always the risk of a new illness or drug that falls through the current tests. There's a reason that most countries ban it.