It is actually called an "addition to tax", not a penalty, and in fact it is merely an interest charge, just like if you don't pay the full balance on your credit card each billing period (for tax, the "billing periods" are the (roughly) quarterly dates when estimated payments are due). If you can make more money elsewhere than the interest charge by the IRS (currently 7%) you are better off not making the payments during the year.
>Health Savings Accounts are the rare unicorn of triple tax advantage: money isn’t taxed (1) going in, (2) while it’s growing in the account, or (3) when it’s taken out.
I see this a lot and it is completely ridiculous. (1) and (3) are the same thing when it comes to your contributions-- there is no scenario where you would ever pay tax on money when you contribute it and also when you take it out. It is only a double tax advantage, not triple. (And the money only comes out tax free if you use it for a limited set of expenses namely health care).