The 2021 Life Insurers Fact Book says it hasn't hurt balance sheets at all.
In 1960, total death benefits paid to beneficiaries was $3.3 billion. Death benefit payouts kept rising throughout the decades. In 2000, total death benefit payouts were $44.1 billion. In 2019, life insurers paid out $78.3 billion and in 2020, they paid $90.4 billion in death claims.
In 1960, the life insurance industry held policy reserves of $98.4 billion and capital and surplus funds of $9.6 billion. By 2019, that number was $5.7 trillion, with capital and surplus funds of $441 billion. In 2020, those figures increased to $6.1 trillion and $454 billion, respectively...
...The CDC's final report shows 3,383,729 deaths in the U.S. in 2020. Of those who died, 350,831 are reported as "COVID-19 deaths". The CDC also recorded 528,891 more deaths in 2020 than in 2019. Final numbers for 2021 are not available yet at the time of this writing...
... If true, then according to the government's own data, COVID deaths represent just 0.11% of the total U.S. population. Let's also assume Kirsch's idea of a 40% increase in mortality in the general population is true. He writes that it would mean 75,000 new excess deaths per quarter. Over the course of an entire year, that's 300,000 new excess deaths.
Add that to the 2020 death count, and it puts us at 3,683,729. Kirsch assumes the 300,000 are not from COVID and are instead from some other new cause.
This means the hypothetical non-COVID/new cause of death represents about 0.09% of the total U.S. population. The combined COVID and hypothetical new non-COVID/some other cause of death is still only 0.20% of the total U.S. population.