This is just math.
If you do the math, 4,000 hours is about 166.6 days. That means you have to record for more than have a year and upload it to YouTube
Let's say you have a 12 five minute videos. You need 4,000 people to watch them all of them, all the way through.
12 x 5 = 60 minutes. Times 4,000 equals 4,000 view-hours.
Yes, this is a very high threshold. But be aware, those channels that are being dropped that could not reach this number were not really making any money. 90% of the dropped channels had never been paid because Adsense requires a revenue balance of $50 to send a payment. And another 9% where making less than $100 a year.