Offer your thoughts or opinion on the input financial query or topic using your financial background.

Why invest for the long-term rather than buy and sell for quick, big gains?
There are many technical answers above , but the short story to me is that very few active fund managers consistently beat the market. Look at the results of actively managed funds. Depending on whose analysis you read, you will find out that somewhere between 80-90% of fund managers in a given year do not beat passive index funds. So go figure how you will do compared to a mutual fund manager who has way more experience than you likely have. So, that in itself is moderately interesting, but if you look at same-manager performance over several consecutive years it is rare to find anyone that goes beats the market for more than a few years in a row. There are exceptions, but go pick one of these guys/gals - good luck. Getting in and out of the market is a loser. This is because there is no way to see market spikes and down turns. There are many behavioral studies that have been done that show people do the wrong thing: they sell after losses have occurred and they buy after the market has gone up. Missing an up spike and not being in before the spike is as devastating as missing a down turn and not getting out in time. There is another down side, if you are trading in a personal account, rather than a tax deferred account, going in and out of stocks has tax complications. In short, a broad based equity index will, over time, beat about anything out there and it will do it in a tax efficient manner.  Exchange traded funds (ETFs) are a wonderful way to obtain diversification immediately at very low cost.