Using basic levels of intelligence. Each of those people, has at the very least 5 times Kage level chakra(war arc Kakashi was a stamina freak), and when combined with Minato, it gave every single shinobi at least 10 times Kage level chakra.
Do you all think, that's Hashirama has at least 100,000 more chakra than the average Kage? Not shinobi, Kage.
Just sit, and think about that.
Naruto in base has 4 times more chakra than Kakashi. Same Naruto, as a kid(13), had enough chakra comparable to 30% Kisame with samehada, the tailless beast.
Naruto at 16 is bound to have as much chakra as Kisame without Kyubi, which is 4 times that of Kakashi.
If you tell me, Hashirama has as much chakra as one of the people Naruto sent chakra to, 10 times Kage level chakra, it was still be a believable but still astronomical amount of chakra.
Enough that even Juubito thought they were trying to use it to tank the attacks
But in no way would I have the low intelligence to think Hashirama has over 100k times the amount of chakra a Kage would have.
Just my two cents