It's not about opinions or beliefs here; there's a hard-coded cap in Bitcoin's protocol that tops out at 21 million coins. But many people forget that Bitcoin is open source. Anyone can poke around the code, do the math themselves, and see that hard stop.  

So when some people claim that developers or insiders could change the 21 million mark if they wanted, they're showing that they obviously don't know what they're talking about.  No such 'limit per se actually exists.  You've got block rewards that keep halving on a set schedule and  past that it's just simple multiplication - the protocol handles the rest.  So if somebody says otherwise, take it with a grain of salt.  The coin count itself might be abstract, but the logic governing it is carved in stone.