Lets say i buy 3 vpns with bitcoin and route them trough each other. Whats the difference from this setup abd tor?
Firstly, if you aren't using Tor Browser, then your browser probably already uniquely fingerprints you. The Tor developers spend endless hours making sure that you look exactly like every other Tor user. With 3 VPNs, the websites you visit will be able to determine this fingerprint and correlate all such traffic. This may or may not be enough to actually identify your real IP address, but even if it doesn't you still stand out from everyone else.
Secondly, you are trusting the same three VPNs for all your simultaneous connections and all your future connections. With Tor, connections to different sites go through different circuits. Also there are thousands of relays that your traffic could go through, not just 3. If there were only 3, correlation attacks become much more feasible and the three VPNs can become targets for state actors (not to mention that some, if not all, of these VPNs may already be compromised/provided by state actors). A VPN probably logs all IP addresses in and out and may be mandated to give up those logs by law. You would have to be very careful about choosing your VPNs. Non-malicious tor relays do not keep IP logs, so there is nothing an adversary can lean on them to give up.
Thirdly, Tor is free, so no need to purchase anything and potentially leave a paper (blockchain) trail. Bitcoin is not an anonymous currency. How are you purchasing your bitcoin? Unless it's with cash, then anyone can track your VPN purchases. Even if you pay with cash (which for 3 VPNs you will need quite some cash) with what internet connection are you going to pay them? If you use your real IP to get their BTC link, you have deanonymized yourself. You could go through tor of course, if they accept tor connections.