You can not assume you can guess read-throughs based on reviews, is my first problem.
It's against their terms to buy reviews, but you still trivially can (and risk getting banned if Amazon suddenly decides to enforce their rules - it's not worth the risk), and plenty of "grey hat" review services exist that costs money and where the provider will "gift" the readers copies bought off Amazon, but where the readers aren't paid, and are at least in theory given instructions that somewhat tries to comply (or pretend to comply) with Amazon's rules. Wouldn't use that either.
If the reviews aren't verified, then ARC (advance reader copies) are also common and accepted by Amazon w/caveats (you need to be very careful about wording, and for KU it's against the terms for you to send the book out while it's exclusive to KU, but you can do it before, or pause KU), and a fairly large percentage who receive ARCs will leave reviews. ARCs is the norm in the publishing industry, and so anyone remotely decently prepared will line up reviewers that have no direct link to sales, and someone with a following somewhere can sometime line up fairly chunky numbers of reviews right off the bat.
But this means the ratio can be far lower. It's likely a lot of the early reviews will have come from free giveaways and early efforts that did not earn the author a single cent and might even have had a net cost.
Without knowing how the author in question promoted their book, it's a guess that could easily be off by a factor of ten. But it could also be better.
$200k is certainly possible. Just rare.
To do well on KU, people also usually focus on maximising page count. That means writing series, and pushing out "box sets" to encourage. It's a very different game from writing standalone novels, and one probably better suited to people already used to the webnovel/serials on Patreon game.
With respect to the Chinese web novel market, my son spends a fortune on it, but it's still a tiny sliver of overall publishing. I suspect it's likely to outpace the growth in the rest of the e-book market though.
It's against their terms to buy reviews, but you still trivially can (and risk getting banned if Amazon suddenly decides to enforce their rules - it's not worth the risk), and plenty of "grey hat" review services exist that costs money and where the provider will "gift" the readers copies bought off Amazon, but where the readers aren't paid, and are at least in theory given instructions that somewhat tries to comply (or pretend to comply) with Amazon's rules. Wouldn't use that either.
If the reviews aren't verified, then ARC (advance reader copies) are also common and accepted by Amazon w/caveats (you need to be very careful about wording, and for KU it's against the terms for you to send the book out while it's exclusive to KU, but you can do it before, or pause KU), and a fairly large percentage who receive ARCs will leave reviews. ARCs is the norm in the publishing industry, and so anyone remotely decently prepared will line up reviewers that have no direct link to sales, and someone with a following somewhere can sometime line up fairly chunky numbers of reviews right off the bat.
But this means the ratio can be far lower. It's likely a lot of the early reviews will have come from free giveaways and early efforts that did not earn the author a single cent and might even have had a net cost.
Without knowing how the author in question promoted their book, it's a guess that could easily be off by a factor of ten. But it could also be better.
$200k is certainly possible. Just rare.
To do well on KU, people also usually focus on maximising page count. That means writing series, and pushing out "box sets" to encourage. It's a very different game from writing standalone novels, and one probably better suited to people already used to the webnovel/serials on Patreon game.
With respect to the Chinese web novel market, my son spends a fortune on it, but it's still a tiny sliver of overall publishing. I suspect it's likely to outpace the growth in the rest of the e-book market though.