Can We Trust Cryptocurrencies?

I think that, you know, can we trust in the currencies that we're commonly using on a day-to-day basis? And will the bottom fall out of it eventually? If the bottom falls out of something, everything collapses. Here's the thing. The creators have fixed the total amount of Bitcoin, for example, as one cryptocurrency at 21 million. What if they're lying? For example, what if the availability of Bitcoins could be increased to more than 21 million? Who says they can't or won't do it just as Craig pointed out,. banks in extreme conditions can and do print more money in the market.