Bitcoin has certain limitations which makes it unsuitable as digital cash for daily payments. As long as the network remains congested, I don't see it challenging Fiat anytime soon. High fees and slow transaction confirmation times only makes Bitcoin good as a store of value. It's better than Fiat in the sense that it's decentralized. Other than that, Fiat is a better choice for stable payments worldwide. There's still hope that someday Bitcoin will become better than Fiat as the project develops over time. The Lightning Network, Taproot + Schnorr Signatures, and many other features will make this happen faster than you could've ever imagined. Who knows what the future of Bitcoin will be?

Nonetheless, we could say that other cryptocurrencies are better than Fiat because of their highly-scalable blockchain networks. Yet, they lack the level of mainstream adoption Fiat currencies have. Without merchant adoption, what use can crypto have in the real world? Time will tell us whenever Bitcoin will be able to outperform Fiat or simply remain behind it every step of the way. Just my thoughts