The correct answer to this open question is the following.
Would you consider this an ethical marketing strategy?
No. Of course not. It is not ethical. However, it is not illegal.
It cannot be considered ethical because this piece of advertisement is playing with the lack and necessity of the poor people of San Dayana.
The lottery advertisement is trying to be lucrative and benefit from the ignorance and poverty of the people of this poor country.
Once said that people are the ones who had the last word on the decision to buy or not to buy the lottery tickets. They know that the probabilities are minimum to win the big prize.
So instead of work, save and invest, or do other legal things to prosper, they prefer to spend their hard-earn money to get the "miracle" and become rich.