I am not entitled to any thing, right? Except if you wish to share with me, an amount of your curation rewards. But it is not automated and certainly not obligatory, correct?
Absolutely correct!
If someone wishes to delegate their hard earned steem power, in order to make an (even small) profit, can it only be done by selling votes (through services such as the ones you mention)?
Vote selling does not need a delegation. It works by giving posting authority to the vote buying service (MB and SS). Profitable delegations cases can be when:-
You delegate to a bid bot (you receive a share of their profit).
You fill an SP lease request on MinnowBooster (you get 90 % of the Steem paid by the person to receive SP delegation).
You delegate to anyone, me for example, and receive an upfront or regular payment for it, as decided and agreed.
I hope your question is answered.
Yes, thank you! Everything is more clear now :)
I wish you a wonderful and constructive day,
Katerina
Thank you, Katerina!