talking about blatantly illegal transactions, like trafficking or drug deals, but if that’s not part of someone’s threat model

I am talking about anything that might become a skeleton in your closet, when political winds change. If you:

• donate to anyone religious, vocally non-religious, political, controversial, extreme, or critical of government.
• are American and can be linked 3.5 degrees of Kevin Bacon to any Russian.
• purchase cakes from bigoted religious Christians.
• bought merchandise of controversial figures
• donated to the guy who taught his pug to Seig Heil and plan to visit Germany.
• transfer money to protesters.
• contribute to public defence funds.
• purchase "suspicious" amounts of nearly random chemicals for reasons you don't care to explain.
• purchase novels with Russian or Chinese themes and undertones.
• do anything your governing body or enforcement division disapproves of.

The likely-hood of you becoming a big enough thorne for governments is small, but they are ultimately the key holder to your privacy. That should be your threat model.

if I choose to run for office

De-anonymizing crypto users is not illegal. Posting it is illegal, but finding out what you purchased for a smear campaign? Totally fine in most western countries. Advanced persistent threats would be that future's threat model. It is not hard for large political organizations to hire teenage nosy geeks to dig up OSINT dirt. Your level of risk tolerance is your choice. If it's too much hassle, it's too much hassle.

That said, the largest governments in the world have signed a cooperative agreement to share and process data they are currently collecting, regardless of the legality of collecting it.

Purchasing privacy coin, using TOR(Yes, in caps. They don't get to set the rules on acronyms.), doing anything "out of the ordinary" will likely warrant investigation into your affairs. Once they have that data, their track record of protecting it is not so good. "The Pentagon", "ANAO", and this one doesn't even mention why the UK suddenly needs a new task force with Russian advanced persistent threats "on the horizon".

Everybody else: If you just don't want your neighbors to know you have a fetish, knock yourself out with lightning and have the package gift-wrapped.