I keep reading that Stock Index Funds are a good way to go. I invest pretty heavily in them. The thing that I dont really understand is HOW they work. For example, I have a lot in VTSAX.. If you look at a chart from the last 10 years VTSAX rollercoasters up close to $40, then back down, then up near $40 again, then back down. Recently it went over $40, but has been taking a bit of a drop and headed down again. I'm in it for the long run so I dont mind the rollercoaster, but how is it possible to end up with more money in the end if it's not continuously improving (meaning always staying above $40, then higher). I know VTSAX doesn't pay much in dividends, so it needs to always be growing for people like me to make money in the long-term, right?
Please correct me if anything above is incorrect.
Thanks!