In my opinion There are several reasons why Bitcoin is consistently on top among cryptocurrencies
Firstly, Bitcoin was the first decentralized cryptocurrency, giving it a first-mover advantage and making it the most recognizable and trustworthy cryptocurrency in the market.
Secondly, the network effect of Bitcoin means that as more people use it, it becomes more valuable, driving adoption and value. Additionally, Bitcoin's highly secure blockchain technology instills confidence in investors and users, increasing demand and value.
Bitcoin's widespread availability for trading on global exchanges has also contributed to its liquidity, making it the primary currency for trading between different cryptocurrencies.
As you mentioned, Bitcoin has a limited supply, which is capped at 21 million. This scarcity has helped to drive up demand and value over time.