Typically, if more people are trading a crypto, it'll be easier to find someone willing to trade with you.
The difference between the estimated buy and sell prices are called the spread. The size of the spread is a measure of the liquidity of the market, or how quickly and easily you can convert between cash and this crypto. Typically, if more people are trading a crypto, it'll be easier to find someone willing to trade with you. This is why you may see smaller spreads for better known crypto like Bitcoin, and larger spreads for lesser known crypto.