Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Does longterm investment in index funds still make sense in a reality of massive algotrading?
Why wouldn't you expect a long-term profit?  Say you buy 100 shares of company X, selling for$1/share today.  You hold it for 20 years, after which it's worth $10/share (in inflation-adjusted dollars).  So you've made a profit, only making two trades (buy & sell).  What the algorithmic traders have done with short-term trades during those 20 years is irrelevant to you. Now expand the idea.  You want some diversification, so instead of one stock, you buy a bit of all the stocks on whatever index interests you, and you just hold them for the same 20 years.  How has what the short-term traders done in the intervening time affected you?