It is just an example: if your 2021 salary income (no other income) is $140k, and if your 2022 salary income is $150k and capital gain is $200k, so your 2021 total income is $140k and your 2022 total income is $350k. But you don't pay any estimated tax on capital gain, since your 2022 salary tax withholding is already more than 2021 tax, so there will be no underpayment penalty. Unfortunately, you lost all the money in early 2023 before filing tax return. 

For such an example, you will owe IRS money (mainly tax on the 200k capital gain), but you don't have money to pay the tax. What should you do? Can you request IRS for later payment (like a loan, monthly payment)?

Particularly for early 2000 stock market collapse of dot-com bubble, there must be many people making a lot of money in 1999 but lost a lot of money in 2000 before filing tax return

Thanks.