The current marketcap of cryptocurrencies is more than $2 trillion and is unique because there is no regulation that regulates it, of course this is a serious problem for us, so there are always scam projects that are very detrimental to investors, without regulation then we walk without direction.
Why having market cap in trillions of dollars is problem for crypto? In fact I am putting it in exactly opposite way: having high market cap such as this makes me think there are big investors, huge support from all over the world for this. The network of crypto is wide spread and there is no kill switch for the same. At this point it’s impossible to turn it off but to continue the way it is. If government starts regulating it then there are many loop holes in the system. Peeps can simply buy and sell stuff online by using third party services and yet paying in the bitcoin. I see no issues so far.