"We estimate that a one-time maximum debt forgiveness of $10,000 per borrower will cost around $300 billion for borrowers with incomes less than $125,000. This cost increases to $330 billion if the program is continued over the standard 10-year budget window. Eliminating the borrower income limit threshold produces a 10-year cost of $344 billion. Increasing the maximum amount forgiven to $50,000 per borrower increases the total cost to as much as $980 billion."
Meaning it's a figure over 10 years. So let's use the main source's numbers instead: $330,000,000,000 / 10 years / 144,300,000 taxpayers = $228 per taxpayer per year. Even better.
And just for fun, let's look at the same calculations using the analysis for "no income cap" and then again for a $50k forgiveness cap:
No income cap: $238 -- only $10 more per person per year.
$50k max forgiveness: $670 per person per year. Obviously more significant, as it's forgiving 1/3 more money on average, but still. Imagine if this policy were put in place for new loans going forward. Everyone in the country could attend college for $670 + tuition excess over $50k, which means most people could do it for $670/year flat.
And of course, these estimates all account for the initial massive cost of existing loans; if it were set in motion to apply to new loans, the cost would decrease over time as those old loans are done and only a smaller number of new loans are created.