Why does the Teiko basketball club have over 100 members? The Teiko basketball club in Kuroko no Basket is described as an incredibly strong team with over 100 members that won the championship three times in a row.

However, only 6 in the main roster and 2 of their senpai(s) are actually shown and mentioned in the whole anime. The other 92+ players were never mentioned and are literally useless. They also affected the basketball in middle school, where they themselves got more and more bored and their enemies gave up before even playing.

So I'm wondering why would 92+ players even join the basketball club when they obviously have no chance to play in a real match?
The second/third string in Teiko play matches against weaker schools. In one of the OVAs (Tip Off) Kise (when he first joined) and Kuroko help the second string in an exibition match. 

Also, first years and even second years would not usually make first string right away in a bigger school, but they still need training so that they can possibly join later.

They could just have joined to play/practise basketball. Remember that it's a club not just a team. I doubt that anyone would even attempt to join if they had to make first string. It's pretty clear playing in matches is a privilge for most people, not an expected outcome.