Many of those present here made similar mistakes with different coins. If they still don't made such mistakes, they will certainly make it in the future. There is nothing to regret - it's common thing.
Most of investors will made it, because they will instinctly buy at peaks, and sell at bottoms.This is one of common basic instinct of investors, not only in crypto market.
Many of the projects will not be around in a few years from now, that's just how the startup world works. And in that regard I don't think blockchain will be much different. They might not drop to zero as some people might see any sort of value, but not all will turn out to be great long-term picks. 
