BNB coin, also known as Binance Coin, is considered expensive for several reasons. One key factor is the popularity and success of the Binance platform, which has established itself as one of the leading cryptocurrency exchanges globally. Additionally, the BNB coin serves various utility purposes within the Binance ecosystem, such as trading fee discounts, participation in token sales, and more, which adds value to the coin. The limited supply of BNB coins also contributes to its price appreciation, as it creates scarcity in the market. Overall, the combination of utility, scarcity, and the success of the Binance platform can drive up the price of the BNB coin.