Monero has a significantly higher "base level" privacy than other cryptocurrencies, and it's great for many use-cases. However, it still has limitations. You should check out the Breaking Monero series: https://www.monerooutreach.org/breaking-monero/
Monero uses special techniques to obfuscate activity on its chain, increasing the cost of chainanalysis significantly. However, for an attacker that is well funded (e.g. NSA) it's likely a very small challenge to overcome.
Besides brute-force tracking of the chain, a clever way to track cryptocurrency users (including Monero users) is to add backdoored cryptocurrency wallets/apps into app stores and capture the data at the point it is created, just as Facebook/Whatsapp capture keystroke input in realtime. This is probably even cheaper than breaking Monero's obfuscation techniques, and also works well against better privacy technologies such as Zcash.
> and also works well against better privacy technologies such as Zcash.
It's not even worth responding to this person.
I'm not sure there is an educational moment with people like this.
For the record, to anyone passing by, I and many others view things in the opposite way. Zcash is less private, it operates in two states with the default state being just like bitcoin, with a separate state having opt-in privacy. Many/most Zcash users think they are using the opt-in state by default which is unfortunate. The Zcash opt-in state is not as anonymous as Monero and is easier to deanonymize and harder to use best practices to thwart. Zcash is developed and run by a US based company which can be much more easily coerced than a distributed team like Monero has doing open source work that collectively funds development when necessary. Zcash organization has budget for advertisement. It is suspicious that Zcash followers present an alternate reality so opposite to this that it is gaslighting, and does exactly what people are worried a centralized VC backed US based company would do.
A Zcash user recently made a challenge for anyone to tell where his coins came from that went from taddress->zaddress->zaddress->taddress. The winner only had to look at past transactions and find the same coin amount to find the original t-address.
That is why privacy-by-default is very important, and why right now Monero should be considered more private.