I'm fine with them, they aren't owned by the government which is great. Anyone can earn some money with them, especially with altcoins that are starting out. There is "no real value", yes, however the value is backed by the same idea paper currency is, how do you think the 1 dollar became well, a 1 dollar. The more there is circulating, the more it's worth, but at the same time it's harder to get. Which is good, keeps it balanced unless you want to go ape shit investing in mining contracts. As of currently it takes years, just to mine 20 dollars in btc. As for buying, it's more secure, at least in my opinion, considering how they work it's nearly impossible for let's say some dude to walk in and be like "hey let's steal this guy's money", as for one it's digital, for two it works on a system where your client mines/solves puzzles only the computer can understand, and if it passes through all the tests, then u get some, however keep in mind with so many people trying to mine or solve these puzzles it's also highly likely for someone to mine the current one your client is looking at before you. With this being said, only way to properly take someone's cryptocurrency balance is to middleman, or redirect the transaction, which is near impossible as is.