For B vitamins, you’ll probably just pee out any excess, so likely you’re just making really expensive pee unless you have a vitamin deficiency.

For the D,E,K,A vitamins, they can actually be problematic if consumed in too high of quantity over a long period of time, due to the fact that they are fat soluble and can build up and cause organ damage.

Of course, that’s only if you’re consuming far in excess of the necessary vitamins for a long period of time. Otherwise just like water soluble vitamins, your body just ditches anything over a useful amount.

Some vitamins that are hard to get otherwise are fortified into common staple foods, especially in developing countries, but with a healthy, balanced, modern diet, you’re probably getting what you need from your food. Unless you have a vitamin absorbing issue, other medical issue, or a lack of food variety.