system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Why did the Separatists join with the Trade Federation?

One of the reasons for the Separatists, from what little info about their motives I could find in canon, is that the Republic was corrupt and unwilling to protect outlying star systems from megacorps, and that the invasion of Naboo in Episode 1 was an example of that. In a Clone Wars episode, they even highlight how, unlike the Republic, they don't work with the megacorps.

But it was the Trade Federation that was responsible for the corruption in the Senate and invading Naboo, and that same Trade Federation built the battle droids they used. Did the Separatists at no point worry that they were joining with their oppressors?

To use an analogy, it would be like if Hawaii got mad at the US for not stopping Pearl Harbor and then joined Japan.
gpt
They didn't. The Trade Federation was (supposedly) neutral. While they did provide resources to the Separatists, they also had a seat in the Galactic Senate of the Republic, and publicly denounced Nute Gunray's invasion of Naboo. 

As for why the Separatists were ok with this arrangement, it's actually pretty simple; They needed the money. Both the CIS and the Republic drove themselves deeper and deeper in debt to the Trade Federation to win the war. If the CIS wasn't willing to set aside their ideological battles they would have lost the actual ones.