1.) It is a giveaway for 3 simple reasons:

• They can participate for FREE without sending Ecency points, and all entries are treated the same way.
• The prize does not depend on how many Ecency points the winner sent.
• Only one person receives the prize, and they are randomly selected.

2.) Ecency does not sell votes. One thing is Hive Power renting/leasing and another thing is vote selling, that's something really simple to understand.

If HP delegation were vote selling, no curation project would be able work on Hive.

• People that delegate to any curator project like OCD, Aliento, Curie and receive an upvote from them would be considered as vote buyers
• Qurator shouldn't be sending 80% of all curation daily to their HP delegators, and Leo shouldn't be sending LEO to their HP delegators because they are actually paying a rental fee to their delegators for their HP.
• Hive Engine wouldn't have a market for HP leasing if that were considered vote selling.

That's why Ecency renting their HP is not vote selling.