Bitcoin and the Dotcom bubble are significantly different in my opinion. If Bitcoin were to fail, the world economy would function as normal, nobody would lose their jobs and a multitude of large companies wouldn't go under like the original boom. I know the Bitcoin investment craze is starting to kick-off, but it's not at the point were companies are investing large portions of their cash into Bitcoin to the point where it would fail and companies would go out of business, it's too volatile to be a trustworthy investment at the moment.
If there are people out there who have invested large amounts of company cash or people who have taken out a second mortgage on their homes to buy Bitcoin, the joke is on them. Because Bitcoin has been unrealistically unstable for a long time now, the current growth can't be sustained.