You might consider the concept of "Normalization of Deviance": https://en.wikipedia.org/wiki/Normalization_of_deviance

I agree people can get used to almost anything. We've all been living through a pandemic. Society made it through the black plague. But part of "functioning" through bad conditions is losing touch with the the possibility of something better.

Apparently [0] some people are genetically disposed to require much less sleep than most, but no, you can't train yourself to perform normally when sleep deprived.

[0] https://news.ycombinator.com/item?id=27471247

You may get used to it, but that doesn't mean the negative effects disappear. 3.5 hours of sleep is well into the territory of chronic sleep deprivation, regardless of your genetic makeup.

There is no known combination of genes that makes 3.5 hours of sleep acceptable. The "short sleep" genes don't shrink the sleep need window that much.

We obviously can't know your personal circumstances, but I would caution that according to everything we know you are likely to pay a price for this chronic sleep deprivation, especially if it continues.

Don't you have better days and feel smarter, when you have slept more? It's a night and day difference to me. With little sleep, work is a chore and spare time is unorganized, with enough sleep I handle both better.