Thats too optimistic...Yes, Cryptocurrencies are here to stay, because it is like opening a pandoras box, like John McAfee said. And it must be so if you understand the differences to the hierarchical old and rotten systems. So over the longterm fiat will go away or become at least very small and unimportant, so will banks, and so on... And real open blockchains, may it be as a currency or some other usescases, will become more established over the longterm. Thats the technology as a whole. But if we are talking about making money of that, than which cryptocurrencies will it exactly be? Btc, Dash, Eth, Ltc? So, that doesnt mean, that many of the todays top 100 cryptocurrencies (according to market cap) will continue to rise in prise over the longterm, or even exist in some months/years. What if those digital assets will behave like the companies and their shares at the stock market in the dotcom bubble. They were all rising like hell, and among them there were companies like amazon which continued the trend, but there were much more going to zero. If you hold on to it thinking it will rise again, not realising that it never had a reason in the first place to rise..other than speculation, and not real usecases, you may realise too late, that maybe most of the todays cryptos wont play any role in some years, and that you took the advise of "having a strong hand" too serious. So I think the cryptocurrency market is in a bubble right now, with most of them rising like 5-50 (for example look at dash, bytecoin, eth, nem,...) times since the beginning of this year. But who uses them? Bitcoin is very simple, without masternodes or any other newer crypto inventions. But it is also the oldest and most mature one in terms of robust technology, users, or real use for payments for example. So I think bitcoin is the least in a bubble right now, and also is the least likely to go away or fall in prise over the longterm. I am not the only one thinking that, have a look what the well-known people in the cryptospace are saying about a potential cryptocurrency or especially a altcoin bubble. For example, Andreas Antonopoulos, said on twitter:

"Some of you are wondering "why are cryptos crashing like crazy?"

Yet you didn't ask "why are cryptos climbing like crazy?"

That's why" (https://twitter.com/aantonop/status/875354397093515264)

Hope i could make my point, and this wasnt too long.
By the way this is my first post on steemit ^.^ Struggled a bit at where to start, and didnt feel ready for an own whole blogpost, so it felt right to share those thoughts here.

I intended to give you some ideas, you might not have thought about before, that could change your investment style. So i hope i could help you seeing this whole space a little bit more realistic.