In my opinion, people love crystals for two main reasons: (1) because they look pretty on a windowsill and/or (2) because they add something to their wellness routine. Maybe they keep a hunk of selenite by their bed for sweeter dreams. Or a kunzite in their purse for self-love. Or a piece of quartz on hand to help them meditate.
There's also a whole class of crystals that are meant to offer up protection — from bad spirits, negative energy from others, downer thoughts. And even if you're not a full believer in the rocks' powers, they can be a way to set an intention, a visual reminder that you are trying to think or speak more positively. Plus, they double as decor.