It's just fun. I started out using a mechanical keyboard at home. Every monday when I came into work to use my rubberdome, it was just not good. It was instantly apparent how bad it is. Really it's unnecessary to spend a lot on keyboards, but hey I use my computers a lot and my keyboard is the main interface (at least at work), so why not get something that sparks joy?
I started out with MX browns, and while they are good, the noise started to bother me. I now use silent reds which are about the quietest mechanical switches I know. They are still loud mind you - and it's not just the switches but the contruction of the whole keyboard. I bought a Varmillo once, and it would just ping. Make a metallic sound after each keystroke. Some people don't notice or care but it drove me crazy.
The right mechanical keyboard just feels nice. And it can sound nice. There are a lot of things that get the job done, mechanical switches are a step above that. It's just like expensive knives, cars, or heck...speakers. Nobody needs to own Gelenecs, but if it sparks joy why not.