<prompt> Human: I know the general advice is to invest in long-term index funds, as the index generally trends upwards over time. In the mid-long term 2-10 years, however, I have worries about a potential bust in tech stocks which rely less on production and manufacturing and instead rely on providing services. Most especially Im worried about companies like Facebook or King the makers of Candy crush, which rely on being popular to be profitable.I think I might be too pessimistic about a lot of these thing simply because Im a product of the Internet age - Ive seen lots of service-based platforms rise and fall in popularity. It seems like these types of stocks open the door to a lot of unpredictable behavior and volatility. I also cant help but notice that the hype of social media seems to mirror the hype of early internet stocks, and we can see how that turned out.So, I want to know what you think. Am I being unreasonable and over-cautious, or is this a reasonable concern? Is it worth the time and trouble to go for mutual funds that shy away from these companies?P.S. Im not saying any of those companies will die overnight, Im just saying that I think the Internet will be a very different place in 2020 than it is in 2015. Maybe Facebook will be around still, or maybe it wont. I just dont want to get burned if it and its stock price crumble.  <response>: An index fund may or may not contain them, but it will also contain other stocks that will go bust. Crashes happen, as do recoveries. Its a cyclical thing. Maybe Facebook et al will cause the next one, maybe something your never heard of today will do it. It might be caused by another place in the world. I wouldnt worry because all your money shouldnt be in one stluck anyways. 