Mega backdoor Roth vs taxable

[Matthew Harrigan]

I am a retirement account maximalist. I want to make sure I'm not missing something.

I can withdraw penalty free from prior Roth contributions and 5+ year old conversions, an inherited tradtional IRA, an HSA with prior medical receipts, among several other options. I have almost zero in taxable accounts outside a savings account. I can contribute to 23500 to traditional 401k, 8550 to HSA, and 7000 to Roth IRA. The question is whether to contribute up to another ~30k via mega backdoor (MBD) or to a taxable account. MBD meaning after tax 401k contributions rolled over into a Roth IRA.

I struggle to foresee a scenario where taxable beats MBD. I can withdraw quite a bit from retirement accounts without penalty. I can contribute 30k this year to my Roth IRA via MBD and withdraw it next year for instance. I probably won't withdraw it, so the long-term tax savings and asset protections are appealing.

Anything I am misunderstanding or not considering?

Thank you