why does Thoreau react harshly when his young acquaintance wants to live life as he does?

Thoreau hated copycats even though his book extolls the grandeur of his own lifestyle. Thoreau felt each man should find his own way.

"One young man of my acquaintance, who has inherited some acres, told me that he thought he should live as I did, if he had the means. I would not have any one adopt my mode of living on any account; for, beside that before he has fairly learned it I may have found out another for myself, I desire that there may be as many different persons in the world as possible; but I would have each one be very careful to find out and pursue his own way, and not his father's or his mother's or his neighbor's instead. The youth may build or plant or sail, only let him not be hindered from doing that which he tells me he would like to do. It is by a mathematical point only that we are wise, as the sailor or the fugitive slave keeps the polestar in his eye; but that is sufficient guidance for all our life. We may not arrive at our port within a calculable period, but we would preserve the true course."