https://www.mistminthaven.com/novels/an-investor-who-sees-the-future/chapter-1 novel
And it's not his health. The foresight he had was just so important/influential that its taking on his health. Like it used a lot of his powers so that's why he passed out. Or that's how km seeing it. I don't think they really explained it in the novel
Im not done. I'm around ch 370 so I'm still missing a good bit.
I think the two are very good. The manhwa is a bit more fun and of course faster.
I think the relationship between mc and his lover is better in the novel, but other then that j think both are very good Nd they did a great job with thw manhwa.
There are a few places where the two are different but none I think is important so far.

The big one is coming! I'm so excited but also I'm gonna be skipping so many ch up to it. But it's so good. I'm just weak