If I take in very low carbohydrates I can't walk. So obviously I need more carbohydrates.
In the off-season I was on 2000 grams of carbohydrates a day and 400-500 grams getting ready for a contest, and my contest condition was better than most, for sure, so my body fat was very low on 400 grams of carbohydrates a day.
2,000 * 4 = 8,000 calories alone from carbohydrates

I think this is not correct because it's pretty hard to consume this and he even states he never went above 6,000 calories
The highest I ever went in the off-season was about 6000 calories. And I generally went below 4000 for a contest.