Most of bitcoin gains are from Foreign exchange currency movements which is not investment exactly. Plain cash can give a return but its not the same as buying an asset or part of a business, most of the gains are from speculation. Bitcoin gains as dollar decline is roughly how I see it.
Some of what we will see in bitcoin price going high is also lost value in dollar. Right now thats not apparent as US dollar has not largely declined. Bitcoin is so small its had to tell as its spread globally with a great many people who possibly can buy up supply or add to it, hence why its so volatile. Investment is a bit more even with regular returns, many more holders not speculators. I dont think bitcoin is a bubble or empty speculation but many maybe a majority still label it like that, obviously it was turned down for a listed exchange traded fund.
I've seen many alts which are pump and dump, having a constant pattern in price movement, making it the ideal choice to make profit from them by just buying low and selling high. Be aware though, while they're great for making profits in short term, they're not ideal for long term investments nor to become used as a store of value. Thus if you're looking for coins that help serve this purpose, you're better off investing into the top 5 cryptocurrencies like ETH and Dash to help secure your investments for the long term.
As Bitcoin's future becomes uncertain due to possibility of hard fork, and scalability issues, investors are moving into altcoins making them rise in price, and bringing a constant stream of profits for those who have invested in them earlier. Just sharing my thoughts.
Are the Top 5 deserved or just there because people follow the hype, thats the thing I would consider most. I dont want to buy into ETH at the top of its bubble if thats a correct description but it could also be a start of wider interest, Im not sure. I would consider the oldest standards best as they will have gone through the cycle as you mention with plenty of time for early investors to sell out. Shake out weak hands as they say.
I have noticed alt coins are generally more popular recently. I wondered if it was just me noticing or that is a prominent effect, not normal for worry or decline in BTC price