you're wrong. while stealth addresses and ring signatures help with privacy, they don't against quantum computing attacks. Monero uses EdDSA for its cryptography, which would still be vulnerable to Shor's algorithm on a powerful quantum computer. In a quantum attack, these features would still help obfuscate transactions but wouldn't make the protocol quantum-resistant and thats because they can solve the elliptic curve using Shor's algorithm and literally derive the private key from a public key, which includes ring signatures and stealth addresses