I don't think that it is the biggest problem. To my mind, the main one is that market is not stable and most people don't believe in crypto and power of coins which make it volatile
Probably volatility may be a problem for some, but that is one of the reasons a lot of traders are in this market, and they are taking a huge chunk advantage of it. However to me, it is not the problem, but the root cause of that volatility, which is high speculative environment and manipulation combined with people's greed are the main problem here. Remove all those aforementioned from the market and you will see less volatility. However, it is a new market, so that would be a lot to ask at this stage until we start seeing real life usage and less speculation.