The various trials and probes serve overlapping purposes:

- Definitely to drain his time and money and attention from campaigning
- To reduce his stature as a candidate and make him appear shadier
- To generate derogatory Trump content for the news cycle
- Possibly to create unhealthy mental stress in Trump so that he breaks or has a medical episode before the election.
- To convince normies that he really is terrible in all ways.
- Possibly to "win" his convictions but more important just to keep up a drumbeat of "Trump bad".
- Possibly in the event convictions are won, to leverage it/them to trigger legal prohibition against him being placed as president.

Your question suggests that there is more than the surface level points to this, and I honestly don't think there is. It's just Trump open season.

They want Trump tied up in court and jailed because they hate him so much. They've been trying to get Trump since he announced his presidency. They know his movement, the MAGA movement, will destroy their world of corruption.

It looks like they're losing and if they put him in jail they'll have created a martyr. I think they already created one already with what they're doing in NYC. They put an extensive gag order on Trump so he can't even talk about the accusations against him.

The case is supposedly about how the Trump organization classified payments to Stormy Daniels as legal expenses, which Trump had no knowledge of yet they want to send him to prison over it. Its absurd, yet allowed to go on to smear Trump.