VOTING BOTS - could please someone explain to me why this makes sense for the vote buyer?

I made a several month trial with different voting bots, different amounts of steem from 0.25 up to 25, different tags and high and low quality content, before and after HF20.

My experience so far:
lost money to a scamming bot
lost money to a bot that was offline (and apparently the bot owner as well as the steemit community says this was my fault as I did not check the profile before)
lost money to a bot that upvoted me only with the same amount I transferred to it (hence the bot got 1/4 of the reward back to itself for curation)
made a return on one bot of ca. 8% for each transaction
made a return on another bot of ca 15% for each transaction.

(Sorry.. I will not name the bots as I already got a lot of fire from a dispute before but this is not a problem as this is not about single bots at all but about bots in general.)

To sum it up all in all I actually lost steem and also readers.
When I did not use any votingbot I got frequent comments on my posts.. using bots I got only bot-followers rushing in with votes before the bot voted (front running) and no comments and interaction at all.

So using bots equals loosing steem equals loosing money. So it makes no economic sense.
At the same time steemians seem to stay away from commenting and reading bot voted content. So again, makes no sense at all.

So please tell me, from the perspective of an author, what is the reason to buy votes... I just do not get it.
Or did I miss something?
No offense.. I just want to understand.