Who knows if 10 years from now, they may discover that high levels of vitamin D may be bad for us, just like they recommended hormone pill decades ago. Or that eggs used to be bad for cholesterol, now they are OK.
I was given prescription vitamin D, but they were expensive even with my co-pay. Now I order 50K IU D3 capsules from Amazon to be taken once a week. My last vitamin D level went from 17 to 79 in a year.