> The issue is that the government cares deeply that you pay taxes in the year that you incur them. The US government, as you may know, has massive debt, and so getting the tax later costs it money in interest payments. They care about this so much that if you owe a lot in taxes, you actually have to pay them in quarterly installments, so the Feds don’t have to wait a whole year to get your money.

Which is very silly, because the government pays a lower interest rate on its debt than the average returns from the stock market. So the government would actually come out ahead to carry more debt now and allow you to accrue more taxable appreciation, because the tax paid on the market gains from the money not paid in tax until later are more than the interest the government has to pay on its debt in the meantime.