The largest-dose individual, non-prescription vitamin D supplement pill I have ever seen is 5000 IU, so you'd have to take 10 of those every day, for months, to develop a toxicity symptom. At that point, the per-pill cost of the supplement and the sheer number of pills combine to discourage overdose.

If you have a confirmed deficiency, a doctor can prescribe a limited course of higher-dose pills to get your serum levels back up quickly.

I take cholecalciferol (D3) and menatetrenone (K2-MK4) daily, along with a multivitamin that was essentially a gratis 2.7-year supply, thanks to a fortuitous coupon + sale price interaction, so it isn't actually just making my pee more expensive. I'd feel wasteful throwing it away after someone paid me to take it home, and it'd be great if it activated a placebo effect.

Also, I can't bring myself to like natto.