I had a similar experience a few years ago when I was ~23. If I got in to work at even 10am, I'd still be a total wreck and mornings were hell.

After my boss gave me a bit of a talking to and futzing around with sleep tracking apps and alarms that woke me up at the appropriate point in my sleep cycle for a while I realised that if I just didn't stay up so late I'd feel better.

It was a bit of an adjustment at first and I think f.lux and exercise helped to modify my sleep habits, but I've been feeling tired enough to just want to go to bed at 11pm and haven't used an alarm in years either.

Obviously I'm older than I was when I was a night owl, but given I was able to make the change in a few months, at the prompting from a former boss, I'm less convinced that it's unchangeable.