> So, what would be the main advantage of Bitcoin over Monero?

* **Bitcoin is more scalable**. Monero inherently requires every full node to maintain an ever-growing database of spent outputs, and is many times slower to validate transactions for. Bitcoin uses a UTXO set whose size is proportional to the number of coins currently in circulation, not its history. Longer term, I believe this means Monero's technology wouldn't be able to sustain the amount of usage Bitcoin sees without seriously hurting its decentralized properties.
* **Bitcoin has a larger ecosystem**. Currencies - especially worldwide currencies - show a strong network effect: nobody wants a currency that nobody wants/uses. In the long term, I expect that this will result in just one or a few cryptocurrencies, and Bitcoin has a much better change being one of those.
* **Bitcoin is less of an experiment**. Monero has planned hard forks twice a year, determined by a rather centralized group of developers. This allows them to evolve much faster, but also means it's hard to consider it a decentralized currency (AFAIK even their developers will say this). For example, a government would likely have far less difficulty to force certain changes into Monero than in Bitcoin due to an ecosystem that is just much less eager to follow one group.

In general, I see Monero as a research project to experiment with better privacy technology, not as a currency in its own right. However, that does not mean the  technology being developed there can't benefit Bitcoin or its users.
Bitcoin absolutely needs better privacy. And I believe it will get it too - partially due to better technology, and partially due to better practices.

Bitcoin is naturally slow to adopt changes, but improvements are continuously being worked on (search for things like MAST, TumbleBit, Layer-2 payments, Taproot, signature aggregation, scriptless scripts, confidential transactions, ...). Do I expect Bitcoin to one day have better privacy than what is possible with Monero's technology today? **Probably.** Do I expect Bitcoin to have better privacy than what is possible with research technology at the time? **Probably not.** And that is fine.