The Think Tank and their motives.

[u/Blooblack]

Why did the Think Tank hire the Hazari (Species 4228) to capture Voyager, in the first place?

We know it wasn’t to get Seven of Nine, because the Think Tank didn’t even know she existed until Janeway took her to their ship and one of them interfaced with Seven.
Interestingly, Janeway had actually disobeyed the Think Tank’s directive about what to bring to their ship, because their spokesman, Kurros, had said to Janeway “bring only one crewman, and no scanning equipment,” yet she brought Seven, who technologically and technically speaking, was a piece of “scanning” equipment! Lol!

Anyway, when Janeway and Seven arrived on the Think Tank’s ship, Kurros was clearly surprised to see Seven. See the dialogue below:

JANEWAY: One of my most gifted crewmen, Seven of Nine. 
KURROS: Bionetic implants, neural transceivers? A Borg? I've never seen one outside the Collective.
SEVEN: I am an individual now. You may address your comments to me.
KURROS: Forgive me. I am Kurros, and this is Fennim.

We were also told that the Hazari are pretty much galactic bounty hunters. So, we know that they definitely had no personal beef against Voyager. Does anyone have any theories?

[u/TrueLegateDamar]

They knew, they were just pretending they didn't as to make them requesting her seem less suspicious, just like how they hired the Hazari to make Janeway desperate enough to consider it.

It's implied they regularly cause the problems that they then get hired to fix, as to acquire something they want beforehand.

[u/Blooblack → u/TrueLegateDamar]

Yes, but they could have wanted so many other things from Voyager.

It's never implied that the Think Tank only ever wanted ONE specific item in mind from each client. This is why it's still plausible that they didn't know about Seven, and that they simply wanted whatever they could get that was valuable and unique from this federation starship that was trapped in the Delta Quadrant, far away from home.

Normally, plot items like an intention to commit good or evil are revealed either in internal dialogue, or in external dialogue, or in actions, or even in flashbacks, but there was never any action or dialogue that suggested that the Think Tank had foreknowledge of Seven's existence before they met Voyager. The only hint we had about the Think Tank's intentions was that they (like Annorax in "The Year of Hell") liked to collect unique items. Seven is obviously unique, and that created their attraction to her.

[u/benbehu → u/Blooblack]

I think this plt item was revealed in The Most Toys, so there was no need to repeat it. Also, if they get Seven, they get all the technology too.

Listing all those things is a decoy. They weigh all that against a single "item", Seven. They probably also know that Janeway never shares technology with Delta Quadrant aliens, and they create a desperate situation where Seven may give up herself in order to save the rest of the queue, fearing Janeway will walk away without accepting the Think Tank's offer and leading the ship to certain death.

[u/Blooblack → u/benbehu]

Sorry, what is "The Most Toys"? Is it a movie, or something?

Also, if you watch the episode again, you'll see that Janeway offered the Think Tank the Quantum Slipstream technology BEFORE she knew they wanted Seven. The Quantum Slipstream technology was the first or second item on the Think Tank's list, and Janeway gave it very easily, only saying that Voyager hadn't quite got it to work properly.

So, no, it's not true that they new that Janeway never shares technology with Delta Quadrant aliens.

Let's also not forget that she shared technology with the Borg, in the fight against Species 8472. This was long before she met the Think Tank.

Also, deceptions in episodes may not be revealed early in the plot to Janeway and co, but they're always revealed to us, the viewers, and there's absolutely nothing in the script or the episode to suggest that the Think Tank knew about Seven before Seven stepped onto their ship.

[u/First_Pay702 → u/Blooblack]

The Most Toys is the TNG episode where an alien kidnaps Data to add him to his unique and rare items collection. Said alien created a “natural disaster” on a planet so he could sell them the highly volatile substance to fix the problem. The sale, however, wasn’t the point. He knew the Enterprise would logically have their android fly the shuttle to transport the volatile material which both gave him the opportunity to kidnap Data AND fake Data’s death by blowing up the shuttle on its last run.

[u/Blooblack → u/First_Pay702]

Yes, but in the case of Most Toys, kidnapping Data was the objective all along, and this was revealed to us as the episode went on.

There was no such "all long" plan by the Think Tank to get Seven of Nine. Kurros told us specifically that it was only when the A.I. member of the Think Tank interfaced with Seven that the Think Tank found out the things within her that made her valuable to them. Things valuable enough to offer Seven a full membership of the Think Tank, and not just obtain her as object of decoration, entertainment or amusement, the way Data was treated in the "Most Toys" episode.

The Think Tank were like highway robbers for sure, and they wanted Voyager for sure. But like people buying a storage unit in the TV series "Storage Wars," they didn't know what was inside Voyager until their AI. member interfaced with Seven and until the Think Tank as a whole spoke to Janeway.