Who cares about giving more money to their friends' posts if there's nothing in it for them? Do you go out and buy a bunch of stuff for your friends so that they can have more things for themselves? Who actually does this?

That's not a good comparison. Like I said in my post steem power is similar to upgrades and power ups in games. People buy it because they like the game and want to gain influence/power in it.

Umm...they don't. Have you been watching vote times?

Are you trying argue that bots will still vote at 30 min if curation rewards are removed?

Yes, it will change because there won't be any users.

The main reason user retention rate is bad is because people don't have fun on this site. What do you propose to make it fun?

How can your investment appreciate when nobody will be using the platform because there's no incentive except for bloggers?

You are not seeing the bigger picture. Steemit is just one site among many other sites that will use the steem blockchain. Many of these other sites will have very different models. Some site will be similar to facebook, where people will just document their lives to friends and family, these people should be able to send a few cents to each other. Do you think these people will want to go through the posts of people they don't know to curate content? The curation reward model is a flawed one for mainstream adoption and isn't going to create significant demand.

The only system that will attract a large audience is one where people buy steem power in order to have more influence in the system.

The problems we see on Steemit are not a result of the existence of curation rewards.

Curation rewards encourages bot voting and discourage people from commenting/participating in the platform because no one votes for comments.
I don't know exactly what problems you are refering to, but curation rewards are indeed not the main issue, the biggest problem is that 99.8% don't have fun because they have no influence on the platform.