Because everything you have said is your opinion.

Well, that happens rather often - people state their opinions. I am sure even you do that from time to time. :-)

Let's start with this:

If you can substantiate with data ...

You mean for example 'your' KE? I doubt that it's a suitable metric to measure the 'value' of a user. It's...

• Incomplete
  It only takes Author and Curation Rewards into account. Witness rewards, DHF rewards, beneficiary rewards, regular staking rewards and HBD rewards are ignored. This distorts the picture for witnesses or people who earn a lot through beneficiaries. Moreover, someone who invested a smaller amount of HIVE years ago and later withdrew a larger nominal amount may still have made a substantial financial loss due to the long-term decline in the HIVE price (meaning they invested more than they withdrew, even if they have a high KE).

• Biased, often misused as a moral score
  Someone who buys Hive directly and stakes it improves their KE, even though they may not have produced anything at all. The content anyone creates — and the users they attract by producing it and engaging with the community — is the immaterial side of the medal, which is completely faded out in the KE metric.
  Many users look only at the number and upvote or downvote accordingly. This is a rather shallow heuristic: A low KE does not automatically mean someone creates valuable content, and a higher KE does not automatically make someone a freeloader.

• Easy to game
  It's relatively simple to manipulate the number. Someone can receive rewards on one account while keeping the stake on another, or transfer old rewards to a fresh account.

• Punishes legitimate life situations
  Someone who created good content for years and later had to sell part of their Hive (for a house, medical costs, relocation, etc.) ends up with a permanently “bad” KE score. The metric has no memory for context.

Another practical issue: In most countries you have to pay taxes on Hive rewards when you receive them — whether you sell them or not. So the idea that people should just keep everything staked and never touch it ignores the fact that many users need to sell part of their rewards simply to pay the tax bill on those same rewards.

In my eyes it's also only an opinion that users with a high 'KE' are the main reason for the decline in Hive’s popularity.

If someone produces valuable content, that is often worth far more than a few HIVE. Nobody would blame the author of a great book for earning money with it, because they created something useful and precious. (For me personally, the value of my account has always been the content it contains, not the HIVE I earned.)

As long as someone creates engagement, attracts other users, and writes things that keep me reading and spending time on Hive, these are immaterial values that I rate higher than a few HIVE they might withdraw for everyday life. (That's nothing compared to the waste of the DHF, for example.)

I know many users who left HIVE (or only write sporadically nowadays) due to the heavy automation of the upvote process. They no longer feel appreciated when writing. Many of them never cared much about earning; they put real effort into their posts, which fewer and fewer people notice.

And it is not the small users who are primarily responsible for Hive's problems. It is the big stakeholders who for years claimed they had to make the rules because they had more "skin in the game" (which is often not that much skin when you put it in relation to their overall wealth — so they are actually less affected by Hive’s failure than many smaller users who have relatively more of their fortune tied to it). What we see now is largely the result of decisions made by them over many years.