Sure - the "average" streak will be 2. But most people then make an error in their logic, and assume that the incidence of longer streaks will be much less frequent than they actually are. There is, of course, a 1 in 8 chance of getting 3 H in a row, 1 in 16 of 4 in a row, 1 in 32 of 5 in a row, etc. All of which still averages out to "average streak length = 2." But you are more likely than not to see a string of five heads together somewhere in a sequence of 100 coin flips. In the example I gave, the team that just makes up the outcome will literally almost never have a run of 5 H in their results.