If you were unable to focus your eyes properly afterwards it means the headset you have tried has been likely poorly adjusted and/or damaged. Typically the interocular distance was likely set incorrectly for you (there is a slider on the headset physically moving the displays & lenses), forcing your eyes to strain in order to see clearly.
Another aspect causing discomfort is for the headset lenses to be
sweaty/greasy/fogged up slightly - again very common when doing mass demos on exhibit floors ...
The dizziness and disorientation depend very much on the content you are working with. This is not universal! So the fact that some demo you have tried made you very dizzy and feeling uncomfortable only means that that demo was poorly made and not that all VR content will feel like that.
In addition, the feeling of dizziness and motion sickness will diminish over time for most people. So don't judge the entire concept on your poor 10 minutes experience that you had in less than ideal conditions.
(I have worked over 20 years on VR/AR, both as a researcher and commercially)
