HEY ,
i have noticed that i'd make more money if i trade altcoin with USDT as it's stable and equivalent to usd ,so i can get my calculations .on the other hand trading with btc isn't that much profitable or sometimes not profitable at all if btc price gone down , so why most people trade with btc !
i think i'm missing something .
Trading volume and the number of available pairs are great factors, but the biggest one is that people want bitcoin not USDT, people have the goal of increasing their bitcoin stash if they wanted to do that with USDT they will take a risk, because if bitcoin skyrockets at that point your efforts could be in vain and you could have less bitcoin.