Maybe you didn’t follow my conversation with Argon earlier in this thread about this point, but I mentioned that it becomes a question of defining biological altruism. Because, by definition, altruism must involve a net loss of fitness for the donor– so if the “spare change” we drop into the homeless stranger’s cup does not reduce our own survival or fitness (i.e., we give out of our surplus), it is not considered altruism.
Of course, there are various parameters in the game theory surrounding the evolution of tit-for-tat (as you know) which include the likelihood of encountering the individual again, and the cost of the altruistic act.
Ha! I like to call lotteries a “tax on the stupid” 
. Again, in this case, one must consider that although one usually experiences a net loss of money by playing lotteries, it may not be the case that the loss of money translates into a reduction in one’s survival and reproduction. Therefore, in most cases (except for a severe problem gambler) there may be no selective pressure against the behaviour. And, I don’t know if “playing lotteries” per se has a genetic basis or not? Generalized “Risk-taking” seems to be a personality trait with some genetic basis, that has selective advantages in some environments but not others. So it may be maintained in a population by frequency-dependent selection?