Is buying crypto with a VPN illegal? No, Buying crypto when using a VPN isn't illegal. In fact, it makes it even more anonymous. No one from your browsing logs could say what, when looking at your browsing logs, could say that you've purchased something.
It hides your IP address to prevent IP tracking by hackers, government officials, and forensic analysis firms, so you can buy and sell crypto completely anonymously (if you avoid KYC/AML exchanges). A privacy-oriented VPN doesn't store your logs and has a kill switch, which helps to maintain your anonymity.