A few comments:
- Dollar cost averaging doesn’t increase the expected value of your investment
- It does reduces the volatility of your investment, in particular mitigating the risk that you will invest the full amount immediately before a crash and lose a large proportion of your value
- A strategy which stipulates that you invest a certain amount every month (or every 3 months or whatever) is good discipline as it avoids temptation to respond to market movements by buying high and selling low. Market trending up, everyone says it’s overvalued? Invest $1000. Market falling for the past 5 weeks? Invest $1000. Market just crashed and there’s blood in the streets? Invest $1000. After 20 years you will have ridden through a lot of ups and downs but you’ll have built up a substantial nest egg.