Why does it seem constantly Israel makes bad deals? Like with Hamas handing over the hostages but Israel has to let loose like 1k?

Because releasing 1k hostages is nothing when you can just abduct another 1k randos again

The vast majority of Palestinians detainees aren't security threats in the first place. Israel has a long history of mass detainment without due process. Most are victims of systematic oppression that has gone on for decades.

If you're looking at the numbers alone, then it might seem like a bad deal. However, trading numerous non-threats, especially women and children, for a few hostages is actually seen as a good deal to them. Israel is able to continue its mass detentions with impunity, so they always have a considerable number of Palestinians they can trade for various reasons.

If this is something you genuinely would like to learn more about, then I'd suggest starting with the following article from Human Rights Watch and then expanding more from that. I didn't pick this article for any particular reason. You can find an incredible amount of information on this topic and this was just the first I found with a simple search. Just be mindful of the information source. It's hot topic with a lot of misleading information out there.

https://www.hrw.org/news/2023/11/29/why-does-israel-have-so-many-palestinians-detention-and-available-swap

Because Israel still has control Gaza and The West Bank. They still have more hostages

What is bad about it, in terms of what they are trying to achieve?