There are many valid strategies on steemit. Your high reputation shows that you have found good ones for you. Leasing steem power is one of several interesting strategies.

The question for many is why to do it.

Some want an immediate profit.

Some want to support steemit

Some want to vote their friends

Some want to reward entrants in a competition by voting all contestants.

Some want to defend themselves against a flagging attacker.

Everyone has their own motive for wanting to be a dolphin for a week.

Whatever your motive, more steem power means more people take notice of who you are.

It’s like buying flowers for your garden. People will notice your house. You will please the neighbours. However you will not make a profit from the flowers you bought unless they increase the value of your house.