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How people will find Monero if there is no marketing?

Word of mouth. Word of mouth during the early adoption stage approximates exponential growth since the rate of growth becomes proportional to the number of existing users.
That's probably the strongest form of marketing when people tell each other their own personal user experiences to each other. Therefore, I think the best form of marketing for a product like Monero is to bring it to the lips of vloggers and perhaps also bloggers with wide audience.