Would using Tor over a VPN be a good idea for crypto trading? I understand (to a point) the advantages of such a setup, but would it provide any real advantages in this case? Is it worth the extra expense?
The above idea was right and I tend to agree that using Tor over VPN is too much safer, you can use Tor alone or even PVN alone and yes, it seems it is an additional expense. If you have an extra budget that might be good because AFAIK, there are some ISPs that block the Tor Network and it will always depend on your network provider. The only way that you can access Tor is to use VPN, in that way, you can completely mask your identities such as IP address or any footprints that you are using crypto for the financial transaction which hackers can trace your transactions.
IMO, decentralized exchange plus using non-custodial crypto wallets are complete can hide your identity, yet we can't possibly hide anonymously but possible can be pseudonymous.
Am I overthinking it?
Lol, yes you are. It's all about how you will use it.