It's a fallacy that you thinks the government would believe these 4 Million addresses are controlled by 4 Million people. If Satoshi sell his coins and he use bank account, it means the government will know how much the money that Satoshi have. It won't be a problem if Satoshi didn't buy lambo or luxury stuffs and choose to live below the income tax or capital gains tax, he don't have to split his coins to 4 Million addresses.
Receive Bitcoin as a reward or giveaway is taxable.
Received digital assets resulting from a reward or award;
Charity or non profit organization is non taxable, as long as they met all the requirements.
Charitable Organizations
Organizations organized and operated exclusively for religious, charitable, scientific, testing for public safety, literary, educational, or other specified purposes and that meet certain other requirements are tax exempt under Internal Revenue Code Section 501(c)(3).