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I don't think you can call harvesting profitable, there are still too few transactions to give harvesting that attribute.
Supernodes on the other hand are profitable for sure but you need a lot of xem to join the program.
If you get a block a week, I say it is profitable. You do not spend any except having xem on your wallet. Your xem appreciates in value over time and is also harvesting which gives you more xem. It is slow, but you can still profit.